We will be dropping of a newly purchased car in Nice in late May and intend to go onto Barcelona for about 5 days before we fly back to the US. Can anyone suggest the best way to get from Nice to Barcelona. I understand the train connections are not very good. Thanks for in advance for your suggestions.
You may consider flying.
Check skyscanner.com for flight prices.
You can travel via train; it will be a long travel day requiring at least one train transfer.
If you have the time, you could spend a couple of days in Avignon en-route to Barcelona.
Have a wonderful trip!