Any overnight trains from San Sebastian, Spain area to Nice, France area? THANKS!
Sorry can't help with trains, but have you looked at Vueling, they fly there for between 85-130 euros depending on what day you fly and what date you fly,, just a thought. A night train may cost more once you figure in paying for a counchette.
To find train schedules for all of Europe, follow this advice of Rick's: https://www.ricksteves.com/travel-tips/transportation/trains/online-schedules. If there is an overnight train, you may find more details about it on the Man In Seat 61: http://seat61.com/ To find flights, use http://www.skyscanner.com.