I'm looking for suggestions for the best, most cost-effective way to travel from Florence to Nice and then onwards to Barcelona. Train? What Euro airline options are available?
This site allows you to check out the European airline options:http://www.flylc.com/directall-en.aspThis site allows you to check out the Europe rail options:http://bahn.hafas.de/bin/query.exe/en
It nearly always boils down to how much time you save by flying compared with RR travel. Often the train is cheaper, but takes longer.
And airports are always a long way from the city center, but RR stations are always in the center.
For the Florence-Nice leg, I would look into train travel. Look up schedules on Die Bahn (2nd link in Kent's post), then purchase tickets on Trenitalia. The site's a little buggy; play around with it until it obeys, or book in Italian. Put in Florence & Nice in the station fields. On the next page, select "Nice Ville" as your arrival station. On the schedule page, sort the trains by number of connections. Click the shopping cart to buy. I found an 8 hour train that leaves at 7:51am with one change in Genoa. Prices: 2nd class: 38E; 1st class: 53.50. You'll need to create a Trenitalia account (free) to purchase tickets.
Catch a plane for Nice-Barcelona. Vueling flies this route.
Currently the Trenitalia site does NOT accept North American credit cards. Simply buy your tickets when you get to Italy.
I agree that the most cost-effective way to get from Nice to Barcelona is to fly Vueling.