Cinque Terre-French Riviera-Barcelona

The Nice to Barcelona is pretty easy except it is going to take 7 hours or more.
More likely Nice to Marseilles or Avignon (change trains) and then Marseillses or Avignon to Barcelona,
The tickets are on sale 90 days in advance more than likely.

To find train routes and schedules for almost all trains in Europe, use the Bahn (German rail) website https://www.bahn.com/en/view/index.shtml, using Rick's tutorial: https://www.ricksteves.com/travel-tips/transportation/trains/online-schedules

Note that this will only show prices for trains that start or end in Germany (so, none of the ones for your routes).

To find Italian rail prices, use Trenitalia: http://www.trenitalia.com/tcom-en. Note that even on this English version of the website, you have to use Italian city names (Roma, Milano, Firenze, Venezia, Napoli, etc).

To find French rail prices, use SCNF: https://en.oui.sncf/en/

To find Spanish rail prices, use Renfe: http://www.renfe.com/EN/viajeros/index.html. If you actually want to book tickets with this, use Paypal rather than a credit card, and you WILL need the tutorial from TripAdvisor: https://www.tripadvisor.com/Travel-g187514-c80518/Madrid:Spain:Buying.Renfe.Tickets.Online.html

Or, for all three of these countries, you can just use Trainline: https://www.trainline.eu/

After seeing both of your posts, if I were you I would skip Nice/French Riviera and add the time to CT or Barcelona, or both.
I would look at flying from Pisa or Florence to Barcelona.

My $0.02

jether2,

"The train routes have been confusing to figure out"

Did you try the DB website that I linked in my reply to your other thread? The train routes are not difficult at all, but they will take some time. I believe I provided a suggested train route from Monterosso to Nice in the earlier reply.

I assume you want to visit Nice for a couple of days, just to have a look at the French Riviera? Nice is a good choice but two nights will only provide a little more than a day for sightseeing, but at least you'll be able to have a quick look.

Travel by train from Nice to Barcelona will take ~ 8 - 17 hours. My suggestion would be to use a budget flight with easyJet on that route. On the present schedules, they have a flight departing NCE at 12:45, arriving BCN at 14:00. If you decide to book with them, be sure to read the Terms & Conditions carefully, especially the luggage rules. I'd suggest opting for Speedy Boarding and advance seat selection, even though that costs a bit more, as that make the experience so much easier.

Schedules for Italian regional trains in May are not likely to be posted, yet, so look now at dates only through Dec. 8. You can request the schedule between any two specific towns, e.g. from Vernazza to Nice Ville station.