New York to Nice is roughly 3,460 nautical miles — a genuine transatlantic sector, and past the usable range of every heavy jet once passengers, baggage and reserves are aboard. Only an ultra-long-range aircraft makes it non-stop, in around eight hours eastbound and closer to nine coming back, because the jet stream helps in one direction and hinders in the other.
Indicative prices start around $104,500–$191,000 on the smallest suitable aircraft, and the full range for every class that can fly the leg is below.