10 day itinerary - input

Or the 4th option: Nice, CT, Rome.

Off the top of my head, I'd scratch the 3rd option. You're already doing a stay in coastal hillside villages with the CT. And an AC stay has to be cut short so you can be in your departure city (Naples or Rome) the night before you go home. Plus it's late to be booking accommodations there.

A,B, or D (4) will all require 2 travel days that will take 5-6 hours each of train travel. So it seems you need to eliminate one out of Nice, Venice, and Rome.

I'm assuming that those 10 days are on the ground in Europe, and don't include your flight days. If they DO include flight days, then you only really have time for 2 places, especially if one of those is CT, given it's distance from a large airport .

My initial impression is that with 10 days you've picked a lot of places that have long travel times between them.

The trip from Nice is probably only an hour to the Italian border but probably another 4-5 hours to La Spezia by train.
CT to Venice is probably 7-8 hours door to door because you are crossing the country at nearly its widest part and has difficult logitisics on each end. Adding the Amalfi Coast is probably 7 hours from either Venice or CT just to Sorrento.

With only 10 days on the ground I would consider how many of those days you want to spend dedicated just to getting from place to place instead of exploring and enjoying.

My $.02,
=Tod

Option B, but add Florence and delete Cinque Terre.

Morning,
Since you mentioned that you really want to see Cinque Terre, and you are going to see friends in Nice, I'd plan on those two, and then add side trips in the surrounding areas .
For example, there are many surrounding towns/villages near Nice that you could visit, easily filling up several days. Add CT and surrounding villages, and a day or two of flexibility for spur of the moment desires, and your 10 days will easily be eaten up.
If this is your first trip, I understand your desire to see as much as you can, but distances may look short on a map, but in reality can take much more time, and a bit of frustration.
Have a wonderful time.

First, look at the transport times between these destinations--you will see that moving really eats into your time. I would choose France OR Italy (unless you limit yourself to very closely linked places).
I have not traveled in France but have done some digging based on others' trips--there are some gorgeous coastal places in France that you could pair with your visit with friends, saving yourself from those long travel days (save Italy for the next trip).
I would look into the Verdon gorge and see if that could be your outdoor fix.
Alternatively, choose Italy (B).

I recommend Option A, starting with Nice, then heading to Cinque Terre, and finishing in Venice. This itinerary balances adventure, culture, food and stunning scenery while keeping travel times manageable. Driving to Rome or the Amalfi Coast would take too long and could feel rushed. Since both are destinations worthy of their own trip, it’s best to save them for another visit.

If you every go to the Amalfi Coast and Cinque Terre there is a lot of similarity and too me the Amalfi Coast wins out. Still, for this trip, don't try to do the coast.

Thanks for all your replies. It probably does make more sense for us to stick to just two main locations with that amount of time. So likely it would be Venice and Cinque Terre or Nice and Cinque Terre. If that were the case, what is the best amount of time in each? We would want to do some hikes in CT so are thinking 3 days and nights there. Then maybe 4 nights and days in either Nice or Venice, and the remainder would be either travel days or a day trip. Would that make more sense?
I still have to decide between Nice and Venice. I'm torn because I'd like to show my family Nice as I used to live there, but think it's a bit more complicated logistics wise. And I also love Venice and the others haven't been there before.

What does the family say? I think you want to make sure you have complete buy-in on any plan that involves a lot of travel. I would be disgruntled to have to spend a day on a train--I can only think about the alternatives, whereas others would not care. Did you compare the travel times? Nice to Venice and CT to Venice both involve several hours of travel.

Starting your vacation in CT has its own set of challenges. Or at least you need to be prepared for a very long trip: fly into the nearst large city that has direct flights from the US. Most likely Milan, but Pisa or Genoa may have something, too, but are more likely to be connecting flights. Then hop a train for a 4-5 hour ride (if going from Milan)

And don't forget to consider the departure point. You can't fly home from CT. You either need to get to a large international Airport like Milan; or be satisfied with connecting flights out if Genoa or Pisa to get you to a hub airport with flights to the US.