How to get started planning trip for Spring 2020?

Any objection to seeing more of the United Kingdom? Someone who has seen NYC hasn’t really seen the USA. Once you’re outside of London, the UK gets quite affordable.

What are your interests? Art? Castles? Food? Family heritage? History? What is the 21 year old studying? IMO Travel is to do things you enjoy not just to go to famous places (OK, some of that is good too). Binge watch RS videos from Youtube. Start with the three travel skills videos. Divide the other travel videos up among the three of you by countries, interests, etc. Make a priority list. Consult Google maps to check out how far apart destinations are. Both the Alps and the Amalfi coast are a long way from London unless you start with a flight to Italy (Milan perhaps). Bahn.com gives great information on how long train travel takes from place to place. Europe is much bigger than most of us think. Consider weather. April can be wet and cold in the north, but great weather in the hotter south like Spain or Italy.

Planning is a big part of the enjoyment. Have fun!

My trips often start with an idea as vague as your "train ride in the Alps" and build outward.

As an example....

Fly into Milan

Train to Lake Como for an Italian experience .... not the Amalfi Coast, but stunning.

Take the Bernina Express into the Alps of Switzerland.

You're intrigued by Versailles. Check out some castles in Switzerland and map a route.

https://www.touropia.com/castles-in-switzerland/

Fly back from Geneva or Zurich.

It's not quite the Amalfi Coast and Versailles, but perhaps you can incorporate experiences that quench each travel thirst.

With London as the start and end and 10-14 days, I would be leery of adding a lot of travel from London to somewhere else too far afield. Most travel to a new location can take ½ day. So imagine arriving in London jet-lagged, and then your son will meet the two of you at the airport and you will all fly to Switzerland or Italy? Or will you enter London and spend a few days and then return to the airport as a threesome and fly somewhere else for a week and then fly back to London, where you will stay, or will you continue home from the airport? My point is only to underscore the layers of logistics you will add because your flight to and from London is not the same location as those you then mention wanting to visit.
Can your son meet you in one of the locations you mention? And if you plan to visit London so he can show you around, is there a location that is easier to get to and from with London as your starting and ending point for your European travels (Alps and Amalfi coast require additional travel than just a flight from London).
I absolutely agree that you should pick places that spark your interest for whatever reason - no need to go anywhere 'recommended'. Im just trying to think of how to maximize your time and energy and minimize the travel from place to place

How about having your youngest leave their (bigger) luggage in London, and fly or train to meet you somewhere else in Europe? That way, you can get started together in, say, Rome or Paris. Then, after some 10-12 days traveling together, you end up back in London, see some of London (or other Britain) together, youngest retrieves their luggage, and you fly home together from London? I suggest this based on three now-adult children who each spent a semester in Europe, who each had a semester's worth of clothes and books to stash somewhere when we traveled together before or after their semester of studies.

I would start by having the travelers list 8 things that they have dreamed about doing in Europe. Then, I would look at the list for possible overlap and see if there is one destination or activity that seems to fit everyone. Realize that travel can take away as much as a day from your trip so plan your locations and movements with this in mind.

I would say, if it were me, I would do more exploration in the UK . 10-14 days isn't as much time as you think it is once you get started planning.

For me the logistics are the hardest part. There are so many places I want to go, but I don’t want to fly from place to place or have long train rides or drive times. For me, that’s a waste of precious time. So, first I’d look at travel times, and decide how far to venture and what your interests are. Will you take trains, rent a car, etc.? How many flights within Europe are you willing to take? Get a good planning map and take a look. Do you want cities or countryside?

If you are coming and going from London you might consider circling from London into more of England and include Scotland and Wales, or going into France or the Netherlands. For me, the easier the logistics are the less complicated the trip. Also, count how many nights you plan to give each location. Give at least 3 nights minimum in each spot and 4 for big cities if possible. You can see how quickly your 10-14 days gets used! Make it simple!

10-14 days, that is very short. Focus on the UK there are so many things to see besides London. That is what I would do if you do not want to do the standard London-Paris-Rome. But Versailles is close to Paris... and that is only a 2.5-hour train ride from London.

For a trip of 21 days we started our planning by having each person bring three suggestions. Then we looked for trends and overlap. For example, when the 25 year old suggested a tank museum we researched the ones in Germany and England. My interest in the Grand National (it's a horse race) became an afternoon at Lingfield Park outside London once we examined the distances involved. We wanted to see interesting sights, spending at least three nights at each location. We wound up starting in London, then training to Bayeux (in Normandy), then training to Amsterdam, and then training to Berlin. We lost almost a whole day each time we moved, so with a trip of 10 days I'd recommend 2 or perhaps 3 locations.

I very much recommend the Bovington Tank Museum in England if you're interested in pursuing that.

Take the train from London Waterloo to Wool, then the taxi to the Museum, ca 7 GBP. This is much more comprehensive in coverage and scope than the one in Germany in Munster/ Örtze, which has changed from when I saw it before.

You could add the tank museum in France as a choice...in Saumur.

I would start by mapping out the two suggestions and see if how far apart they are and if the travel time is something you want to do. When you have never been to Europe you do not realize that a travel day (especially between London and Amalfi) is a throw away day, even if you fly rather than take a train, considering how early you need to be there, getting to and from the airport etc. MAP IT OUT you will see how little time you really have keeping in mind 2 nights in the minimum in any place.
So landing in London you probably want to spend 2-3 days there, travel day to X, 2-3 days at X, Travel day to Y, 2-3 days at Y=11 days!
Not sure if your 14 days includes your travel days, so that would minus two days leaving you with 12 days.
There is nothing wrong with London, Paris and Rome, which can all be done by train.

Vienna and Salzburg-Schonnbrun Palace in Vienna and the Alps near Salzburg.

From London, you can take in Canterbury, Cambridge, Oxford, Bath, Salisbury, Stratford Upon Avon, Windsor Castle, Blenheim Palace.

I too would suggest staying in U.K. Windsor castle and Hampton court are fabulous castle visits.
Train it to Bath then go south along the water to Cornwall and Dorset. Also include either Cambridge or Oxford for wonderful university town visits.

Do you have to end in London? Can't you start in London, then split up at the end of the trip, with your child going back to London and the rest of you going back to the US from your last city?

These kinds of flights (say, into London and out of Naples) are called "open jaw." To find them, use the "multi city" or "multiple destinations" tab in airline websites, Kayak, Google Flights, etc. Don't look for two one-way fares as that's usually far more expensive.

If you need inspiration, look at videos in addition to reading books and trip reports. Rick's videos are here: https://www.ricksteves.com/watch-read-listen/video/tv-show

One other thing to consider is weather. Are you more bothered by "too hot" or "too cold?" And how do you define these things? Will rain ruin your trip (it does for some people)? How important is predictable weather? Everyone has different preferences in this arena. You can look at actual historical weather for various years (much more useful than historical averages, particularly with climate change) at https://www.timeanddate.com/weather/

For example, here's London for April 2019: https://www.timeanddate.com/weather/uk/london/historic?month=4&year=2019

Wow! So many great tips. Thanks so much. I have a feeling this will be a great trip no matter where we go.

Here's something to consider ... fly into London (I am assuming you would stay there for a few days ... if so you will need to pay their air passenger duty from LHR which can be brutal) ... take the Chunnel train to Paris and see Paris (and Versailles) for a few days, then take a train to Zurich (with an optional few days in and around Strasbourg) ... train to Chur where you catch the Bernina Express to Tirano (don't forget to stop in St Moritz for a few hours) ... Tirano to Lake Como area (Bellagio is beautiful), then on to Milan ... doable in 10 days, better if 14 ... fly Milan to LHR then home (if you are travelling thru ... 24 hours or less in London ... you don't get hit with that duty) ... hope you post the final trip plan.

I'm like Nick. Start by figuring out what you would most like to see. Rick Steves videos can be streamed on your computer from this sight ("Watch, Read, Listen" on the left). Watch a bunch to see what resonates with you - Castles, Palaces, Art Galleries, Parks, Nature, Festivals, etc. I also go to the library, check out a bunch of travel guides and peruse them for ideas and tips. I'll then decide which book was the most helpful and buy one to take on my trip (I prefer if it's in a digital version so I don't have to pack anything).

I often use Google maps and put a green flag on anything I might want to see. Then see which of those I can string together in a logical itinerary.

Don't try to see everything, instead focus on a few things and enjoy them. It's easy to turn everything into a blur by trying to cover too much ground too quickly. Consider this your first of many trips to Europe. On future trips you will see different things on your list (all those Google Maps flags that are still green).

May is the nicest month for travel in the UK/Ireland (least rain). If you don't want to worry about languages on your first trip, that may be a great option.

One of my favorite experiences was the April Fair in Seville. In 2020, It starts April 26 and ends May 2. It's a great time to be in Spain. It will be warm but usually not really hot like the summer months.

I would do 1/2 in UK, 1/2 in France. Travel on the Chunnel is fast.

Minimize your changes of location. Think "day trip" not "new hotel".

With your kids, consider hostels. There would be other young people there. For you, a person of a certain age, you can actually rent rooms in the hostels, rather than staying in the bunk room. But there would be lots of other young people there. Plus hostels are less expensive.

One other point:

Your biggest problem is FOMO

Fear of missing out.

You will think "If I go to X, I will miss Y. So I will do both". This is a common approach, but makes no sense.

Every location has lots of things to do. London (and side trip to Bath or Cambridge) and Paris (side trip to Chartres or the Loire valley) both have enough for plenty of interesting things. You won't see Rome, but you will see the little details and get to know these places better.

When my daughter was in Paris for her junior year abroad she was ready to get out of France for a change when we arrived at Christmas. So we flew into London and met her there. We then spent the next couple of weeks in London, Edinburgh, York and then back to London where her BF flew in, spent a few days with us and then they headed back to Paris for New Years and we flew home. So you might consider that he will not want to stay in U.K. at that point. So meet him somewhere else and explore a new area. IMO. YMMV