If you had 10 days the middle of March would you go to Europe?

Short answer: absolutely!
I haven't been to those 3 yet, but I have been to Sicily and Spain (mostly Andalusia) in March and thought the temps were just right if you like things a bit on the cool side.

While I've not been to any of the 3 locations you mention, I'd vote yes for Europe in March. I've been to Paris for a couple of weeks in March and early April. That year it was chilly but not cold enough for me to need a winter coat. I did have a waterproof outer shell, a puffy vest and Smartwool glove liners I wore at various times...mostly as I moved North to Belgium and Netherlands. I am also pretty cold tolerant. Paris was sunny most of the time...well, sunnier than Coeur d'Alene that time of year, lol!

I’d go to the National Hunt Festival ( steeplechase racing ) in Cheltenham, England.

We went to Greece in late March a few years ago. One day of rain but otherwise the weather was beautiful and the spring flowers were blooming.

I would go to Portugal or Puglia, wonderful places to visit .

I’ve been to Portugal in March, and saw orange trees with ripe fruit on them. I really loved Portugal, for many reasons.

Much of southern Europe can be delightful in March. Usually fair weather (though be prepared for some rain just in case). Few crowds. If that's when you can go, it's not a bad time to be there.

But...I always feel 10-day trips are quite short for Europe (you'll burn a minimum of two days, maybe longer, with transit and recovery, so your number of full, usable days shrinks even more). You'll get a better value from your flights if you can extend your trip (or go at another time when you can stay longer that 10 days).

Are you 100% sure that your flight credits will go really poof and turn to dust by end of March? It's worth double-checking to find out for sure, and maybe calling to ask again nicely. Most airlines have extended "must use by" dates for flight credits, and you might find you have more time to make use of them.

I love going in March or April. So many of the comments from people on this board are because they go in summer when it's high season. I've found residents are usually friendlier and more relaxed during the low season.

For many Americans, they can only take a week's vacation to Europe. So go!

need to use by the end of March

Does that mean you have to travel by the end of March or just have to book a flight by the end of March ... if it's book a flight, maybe look for a good deal on a flight in March/April/May and/or wrap your time off around a holiday to get an extra day or two (assuming you are not retired and still working for the man) ... the later dates will also open up more places to go if you are looking for a warmer region ... either way, I'd vote for Portugal, can't go wrong hanging out in the Algarve.

We did Greece in March a few years ago. It was fantastic. Not crowded but still lively. Santorini was excellent that time of year - no crowds.

Of course I would and I’ve done so since I was 12. My parents introduced us to the greatness of European travel in March because that’s when spring vacation was from school — mid March! Pre-pandemic, most of my European trips were in mid March because I don’t like summer travel with masses of tourists. I’ve visited England, the Netherlands, Switzerland, Germany, Austria, Italy, Spain, and France in March.

The only warning I would give is if Easter is in March, the week before Easter (Holy Week) and the week of Easter Sunday are crazed at airports. I learned that the hard way.

Thanks all.
Yes I’m sure I need to use them by March 31.

10 nights boots on the ground not 10 days total . We might do 12 nights boots on the ground.

We really want to go somewhere we haven’t been so most of Italy and France are out for this trip. Looking at the Canary Islands too .

we’d like some activity - hiking & biking

Normally, I much prefer going in the summer, but if the trip were to be only in the middle of March, then I would go first choice to Paris and 2nd choice London. London. With just 10 days, I would pick only one place. That would be Paris.

We always have often traveled the last of March because the lower winter airfares were in place. We also like traveling in October.

And Spring is a great time to go to Europe, especially if you're going to the southern cities/countries.

Airfares again bump up again on June 1st. But you can get into some hotter weather in June.

I went to Spain once in March, Barcelona, Valencia, Malaga, Sevilla, Cordoba (3 weeks+). Andalucia is the warmest driest part of Europe. Barcelona was mild, sometimes a chilly wind, especially in high places like rooftops, hills. Fleece jacket, winter gloves and scarf were all I needed. (I didn't wear them again after I left Barcelona). Valencia has an extraordinary celebration every year March 15-19, Las Fallas. I was there for 3 days, left in the middle. Fantastic, but very crowded, not so much at the beginning but by the time I left, very much so. There's lots to see and do in the city other than seeing the Fallas (fie-yas) and some of the parades and fireworks. There were orange trees blossoming all over and the heady scent filled the air (same in Andalucia). BTW orange trees usually have oranges on them most of year. Once I was in Andalucia in February and they were dropping from the trees, saw one bop a tourist on the head. When they start to make a mess on the pavement, the city will send crews around to shake the oranges off and collect them. I think they use them for fertilizer. By the end of the third week of March, it was so warm in Sevilla that I wished I had a pair of sandals with me.

March is still low season so fewer tourists and low hotel rates (not Valencia during the festival, but very nice hotels are affordable).

I also spent 2 weeks, mid-March in and around Nice. Warm, sunny, no crowds to speak of (except for the Irish bars on March 17 :-). I started with 2 days in Marseille and the only time it was cold was about 4 hours of the mistral. Even then it was sunny and bearable.

Those would be my top 2 picks. Greek islands to consider - Santorini (but there will be lots of tourists if cruise ships dock and it's likely in late March). You could easily spend 7-10 days on Crete, with some good hiking. Athens needs at least 3 full days.

I'd leave the Amalfi Coast to later in the year, when the ferries start runnning, usually early April, or a week or so before Easter - whichever is earlier.

You said the Canaries, but ten days is a lot. Splitting the Canaries with Andalusia is a bit short for Andalusia. I'd go to southern Spain the whole time, or Greece, or Portugal with a stop in Madeira on the way over or back.

The various islands are quite different from each other, so I wouldn't say that 10 days is too much if you're happy to go island-hopping in the Canary islands. To me it's a good idea! Not as "typical" a destination for American visitors.

Somewhere warm

We would definitely do a nonstop Delta A350 Premium Select RT DTW-CDG just to revisit our favorite museums to catch up on works that have returned from loans, or new exhibits. For instance, Musee d'Orsay has important Renoir and Millet works returned and there's a new Nabi exhibit room. Then we would add some new discoveries and visit some expat friends in the Marais. Of course the climate would be very similar but we tend to like cooler weather.

In a heartbeat! We have traveled to France in March and loved it. I am not a warm weather person, so would go anywhere in Northern Europe, but that is just my personal preference. If you don't mind cold, have you thought about Iceland? Great time for the Northern Lights.

Thanks again for all your thoughts - France is really not an option for this trip - we want to try something new. We’ll look more at Spain and Crete.

Museums are not our thing but we have been to the top museums in France and Italy. Thinking that march weather will be cool - we’d like to hike or cycle some.

Thanks for the comment about the ferries on the Amalfi coast.

I didn't end up hiking when I was in Andalusia, but lots of outdoor companies seem to have tours there.
https://andaluciahiking.com/best-hikes-in-andalucia-spain/

Another enthusiastic vote here for Canaries. Many islands, each one very different, surprising diversity (and lots of other surprises, too) plenty of things to see and do. They are NOT a "small place." Only challenge would be getting there and back efficiently (time-wise).

What airline are your expiring flight credits with? I'm guessing maybe United (because they have a flight between Newark and Tenerife, which may have given you the idea). I believe that flight only goes seasonally; schedules look like it only starts in the last week of March - so while you could in theory fly back home directly from Tenerife, for your outbound flight you would need to fly to Europe first (or Morocco...see below), so getting there would be a bit of a slog, eating into your usable time a bit.

Getting to any of the Atlantic islands is relatively easy and quick from Europe, usually a bit more of a chore from North America (in most cases, you need to fly to Europe first, then turn right around and fly west 1/4 or 1/3 of the way back across the Atlantic).

You know, end of March might also be good for 10 days in Morocco. It won't be uncomfortably hot and 10 days would give you enough time to do the place justice. As long as you are up for a little adventure, and don't need a "conventional" trip to Europe (cathedrals, art museums, and other clichés), I'd be very tempted by the Canaries and Morocco (you can actually do both on a single trip, there are cheap flights between them, but with just 10-12 days on the ground, I'd pick one or the other, since each has plenty to offer).

I have not traveled to Europe in March. We prefer September to October. My preference for travel in the Spring is for warm moderate weather. We have enjoyed, Hawaii, Australia, Cook Islands, New Zealand and Caribbean. I too would be tempted to go to the Canary Islands for your time frame. It’s a destination we have considered! Edited to add: https://en.m.wikivoyage.org/wiki/Canary_Islands - Intriguing.

David - delta airlines. I think I’d have to get to AMS or CDG and then find a flight to one of the Canaries. Morocco is one place my husband would love to visit but honestly I fear it’s above my travel skills. I’d have to find a tour.

We could do 12 nights but our spring is busy.

We are not interested in places like the Caribbean or the Southern Hemisphere as it’s high season in both regions. We have been to NZ and AUS not to mention we are pretty regulars to the Virgin Islands.

I've done 10 days in March in Greece and it was beautiful. Sunny most days and the flowers were blooming

Donna, I don't really think Morocco is beyond the travel skills of most people who can manage independent travel to all sorts of places: can you manage Barcelona, Naples, Sicily, Athens, Istanbul? If so, then you would probably do just fine in Morocco. Like anywhere else, it requires you apply some common sense, but it would feel surprisingly familiar in some ways. I think most of us North Americans fail to grasp that Morocco is in many ways akin to "Europe's Mexico." That's a vast oversimplification that does not do Morocco justice (or Mexico for that matter), but there are a LOT of parallels, and Morocco is a major "cheap fun in the sun" mass tourist destination for western Europeans...think Cancun or Cabo, rather than Kabul. I've been several times and never felt the need for a tour.

There definitely is some presence of crass, mass tourism in either destination (just as there is along Spain's Mediterranean coast), but it's easy enough to avoid and focus on the good stuff (both destinations have plenty of that).

With Delta flight credits, you could get to Spain, which would be one of the most logical jumping-off points for the Canaries (or Morocco). There are cheap (surprisingly cheap) flights to the Canaries (and multiple cities in Morocco) from all over western Europe, so if getting to Spain is hard, there are lots of flights from major cities further north.

If either the Canaries or Morocco call to you, you could do either. Get yourself a good guide book for either/both of them and start researching (sadly, there's no Rick Steves book for either, but there are other good guide books).

Back in 2014 during my working years, HR told that I had a weeks carryover of vacation that I needed to use during the 1st. quarter of the year. Called the wife and we booked a flight to Paris (non-stop out of IAH) and found a AirBNB that we could book for the entire time we were in Paris. If 10 days plus travel time is all you can do right now, then go for it.

Thanks everyone!

Absolutely mid March would be a great time for southern Europe! I've been to both Portugal & the Amalfi coast in mid March, neither was cold though I would take a rain coat & puffer vest. After decades of European travel, when I finally visited Portugal, I found it charming. Cheaper & fewer tourists than Spain (where I biked a month around Andalusia in March, one day of rain), not as many famous monuments, but the smaller towns were delightful. I never had a bad glass of 'house wine', nor an expensive meal outside of Lisbon or Porto. We took a lot of day hikes, I stayed with friends, I'm sure there would be specific suggestions if you decide on Portugal. Good Friday is April 7th, so that week will be busy anywhere you go, but sounds like you'd be home by then.
March will still be high season in the Canary Islands, with many Northern Europeans (like my Swedish relatives) spending time there to escape the cold.

Yes!

I was in Portugal last March and I’d go again at that time, no question. We mostly stuck to Lisbon and the center of the country. I’m sure seaside beach resort towns are dead and it’s definitely not beach weather, but for city and town sightseeing it’s nice. There was a heavy rain day, pouring, cool rain, which is not my favorite, but otherwise it was very nice.

I would check Nice and surrounding areas. We were there in Aug - hot and crowded as hell - but it seemed like a great place to visit during off season

Lagos, Algarve, Portugal.

Well, southern Europe, yes. I lived in Heidelberg and Bitburg, Germany for 8 years, and my recollection is the weather isn't so great in northern Europe during March. If you're mainly focused on indoor activities then it wouldn't matter so much.

the weather isn't so great in northern Europe during March

On the contrary, the weather can be great in northern Europe in March. It can be a great time to explore the area.