airfares high to nice france

My standard advice is to get over the Atlantic on the "best" flight for you. "Best" is very subjective, of course. Cost, preferred airline, direct flight vs change, legroom, whatever. Usually, but not always, these flights end up at major airports like Heathrow, CDG, AMS and Frankfurt. From these, you can get where you want to go by train or "domestic" flight (booked on a separate ticket, "self-transfer"). Of course, for some people, the best flight is whatever series of flights on one ticket that ends in their destination city. So my suggestion is that you look for a good transatlantic flight that arrives within reasonable striking distance of Nice and connect by train or a separate flight. A good way to find these flights is to search on Skyscanner from your home airport to "everywhere" and pick the first European country, which is usually the UK for me.

How soon are you traveling?

I set Google Flights alerts for finding best fares for my dates.

And I check my preferred carrier/route frequently. My last trip into London and back from Paris, premium economy on American Airlines was showing $2200 and up round trip for weeks. One day the fare dropped to under $1400. I grabbed it. The next day it was over $1800 and started climbing back up.

Good luck!