2 week trip to France, Italy, and Switzerland

Help us learn more about you in order to make some suggestions. What are you interested in? Why did you select Nice as part of your itinerary? Have you read a guidebook or some articles, or maybe watched a travel program, that are piquing your interest in going to Europe?

Where are you flying from?

You could fly into Nice, requiring a connection elsewhere in Europe. Here is a sample itinerary.
Nice - 3 nights
Sant Maria Liguria, Italian Riviera - 3 nights
Milan, Italy - 2 nights
Varenna on Lake Como (or maybe Bellagio) - 3 nights
Train to Pontresina, Switzerland over the Bernina Pass - 3 nights
Train to Zurich via Chur. Fly home from Zurich.

Adding to Sam's great ideas- (Sam is a very knowledgeable contributor.)
After the incredible Bernini Express train route,
We took the train from Pontresina to Murren. It was about 6.5 hours, and quite pleasant, (our only long travel day.)
Then maybe to Lucerne, as it's easy to get to Zurich airport from Lucerne .

Add as much time as possible.......

I'll attach my 2021 Trip Report, maybe some part of it will be useful to you. Obviously, ignore the COVID references- thankfully.

Have a wonderful time planning.

https://community.ricksteves.com/travel-forum/trip-reports/lucerne-62eb4d28-60ab-4837-b4b4-91a2486eb732

Focus on the riviera in France, Venice in Italy, and the Berner Oberland in Switzerland. Good airports to fly in and out of are Nice, Venice and Zurich. Easyjet flies nonstop between Nice and Venice. Swiss Air between Nice and Zurich and Venice and Zurich. If flying home from Venice you do not want to take an early flight because water taxis are expensive. You want to take a bus from the lagoon to the airport if you’re on a budget.
Allow a minimum of four nights for Nice, three nights for Venice and five nights for the Berner Oberland. When visiting mountains you need to add an extra day because the weather rules.

I would do 4 nights in Nice (so 3 full days) and then go to the Italian Riviera, Cinque Terre and then Florence and fly back from Florence.

Nice 4 nights

Santa Margherita Ligure 2 nights (visit Positano from here)

Vernazza 3 nights (visit the other Cinque Terre towns from here)

Florence 4 nights

So maybe leave Switzerland for another trip.

By keeping it to 4 towns in a somewhat confined area you will limit the amount of time lost traveling from town to town, from hotels to train stations, from train stations to hotels.

How convenient is it to travel from Nice to Santa Maria Liguria? Sounds like multiple connections are involved which is never fun. The more you move around the harder it is when hauling luggage.

@ MaryPat It's about 4.5 hours with a change in Genoa.

Per your update, looks good. The transfer from Lake Como could be a little awkward but doable. You should decide on a location on Lake Como you want to stay. Its a big lake with various transport options depending on where you will be.

Grindelwald would be my 4th choice of places to stay in the Berner Oberland, after Muerren, Wengen, or Lauterbrunnen. The first 2 are car-free and up on the mountain. But that can decision can wait.

Train travel is not difficult for this trip. Maybe now decide where on Lake Como you want to be.

You could fly on Swiss from TPA with a change in Zurich on the way over, and get a nonstop on your return. Their prices seem to be as good as anybody else for a May trip.

plan to spend 2ish weeks in Europe

Marco and Sam came up with 13 & 14 night trips.

Cannot help but wonder if OP's '2ish weeks' is that many nights in Europe

We are feeling overwhelmed trying to put together our itinerary as first time planning a trip like this and have no idea where to start

Decide how many nights you will be there.