Amsterdam, Paris and ??? Help choosing last location, please!
 

We are traveling to Amsterdam and Paris with our two teenage daughters in mid-July. We will have 4 nights left to spend somewhere. I'm looking for suggestions for a place that would be warm and relaxing with plenty to do. I was considering taking the train to Nice and flying back to US from Nice. Someone mentioned the Normandy area, but am thinking that wouldn't be so good for 4 nights with teens. I don't want to rent/spend a lot of time in a car. Suggestions, please!

How about London? Easy train ride from Paris and a great place to go with teens!

How warm do you want it and what do you consider relaxing?

Nice is a good warm option. You can take day (or early evening) trips on the local trains that run up and down the Cote Azure. And it is easy to catch flights out of the Nice airport without having to go back to Paris...

We have decided to add Nice as our last stop and fly home from there. Any favorite spots to stay or nearby towns that we should definitely see?