24 Days in Europe - Itinerary Tweak/Help needed

Sounds like you have a good itinerary. It's well thought through and planned. Never been to Nice, so can't help you on that leg. Are you going to have the car all the way to Rome?

I'd skip Disneyland... but to each his own. My kids who were 11 and 14 thought one day there was more then enough. You are giving it two? I would spend the extra day in Paris,, three days will barely allow you to scratch the surface,, perhaps go to Paris a day earlier and maybe take a daytrip to Versailles instead.

Before Italy, looks OK to me (never been to Italy, so can't comment). If you end up tweaking the schedule, I would try to keep as many days as possible in the Lauterbrunnen area. Weather will dictate your schedule here more than in any other location, so keeping the most days possible will allow you to remain flexible.

Your Itinerary sounds great to me. Very Doable. It's nice you have the week in Switzerland in the middle to give you a break from the cities. You probably would not use a car much in the Lauterbrunnen Valley, and taking a train from Geneva would be very easy. I agree you should spend at least 5/6 days there as you never know what the weather will be.

For your base in the Berner Oberland, I would consider Lauterbrunnen, not Interlaken. Interlaken is very touristy. I prefer to stay up in Muerren. It would also be a good base. Lots of places to stay, restaurants and a small grocery store. Gimmelwald is also a nice town to stay at. Check out Rick Steves' tour book to see what accommodations are available. In ref to a rental car, you could use one for 3 days in the Florence/Tuscany area to see hilltowns and the countryside. You could rent it at the Florence airport after visiting the city. Then return it at the Orvieto train station and take the train into Rome. Check AutoEurope online or call them.

Thanks for the wonderful suggestions guys! 1. We are really not sure if Nice/South France needs 3 days, most of people we talked to were under the opinion that Nice/SF is too crowded and the 3 days is best spent elsewhere. Would you suggest dropping Nice/SF and adding up 1 day each in Paris, Switzerland and 1 day in Florence? 2. As for Disneyland, i am travelling with my 20+ year old kid (my wife), no arguing with her! 3. We are planning to go by Train/flight wherever possible France (Paris/Nice) till Geneva (Easyjet showed up cheap flights) Lauterbrunnen/Interlanen to Venice - Train. This way we avoid renting a car in one country and dropping it off in another, heard its a pain. 4. Would 4 days be ok in Florence considering we are visiting Pisa + Tuscany.
5. We are considering Lauterbrunnen, but most of the apartments are booked, busy season :(

Nikolai, I think your idea about dropping Nice and adding the days to Paris, Lauterbrunnen and Florence/Tuscany would be a good idea. For myself, you could never have enough days in Tuscany. Actually, it would also be a good idea to spend one night in Orvieto (accessible by train) on the way to Rome. It's a lovely quaint, small hilltown. Maybe take a day from Lauterbrunnen, just a thought. For Lauterbrunnen, I would suggest posting a new question specifically asking about apartments/lodging in Lauterbrunnen. You can also try vrbo for apartments.

@Denise: Thanks a lot for your help.
I will probably add another day in Tuscany or in Orvieto. I will tweak and post the plan :)

Also, August 1st is a Switzerland National Day. Is it worth extending a day (and leave Switzerland on Aug 2nd) for the parade/fireworks etc?