Paris to Geneva to Turin to Nice to Andorra to Barcelona?
 

Anyone here done something like this before? My guess is that it would be best to take the train for this trip? If so, how can I book the train to go to all of these places? If I can't take the train, which bus should I take?

Thanks.

I don't think there are any trains to Andorra, so there's that to start.

I wouldn't consider the train but just rent a car. Depending on the period you want to travel traffic should be fine, as well as weather conditions which might be a bit wintery on the mont blanc but other than that pretty mild.

Nice to Andorra - you'd be better off going through Barcelona.

Technically true, but there is a station just a few kilometers east of the border called Gare d'Andorre-L'Hospitalet. I only know this because many years ago I was on a train from Paris to Barcelona that happened to break down there. Whether there are any buses into Andorra, however, I don't know.

How is that possible when Andorra is like in between Nice and Barcelona?

It is certainly possible to train Nice to Andorra - it is by far the best option I'd say. OK technically there is no railway line into Andorra, but there are two routes that take you near the border, only needing a short onward bus or taxi journey into the country. Check the below link:

https://www.seat61.com/Andorra.htm

For train travel in general Seat61 is brilliant and has all the information you might need to know. Train travel - with dozens of national networks and websites where to book - can be tricky for those outside of Europe, so just read as much as you can on Seat61, starting with the two links below.

https://www.seat61.com/Europe-train-travel.htm
https://www.seat61.com/Europe-train-tickets.htm

If you want to look up train timetables, http://bahn.hafas.de is the website to go for the entire of Europe. Note however that it only sells tickets to/from Germany, but it can look up timetables for all the journeys you might want to take in the countries you mentioned.

Even though the earlier suggestion to do it with car is a good one (exploring the Pyrenees and beyond by car is by far the best) I don't think its a practical solution for the OP as rates for one-way rentals/drop off in a different country are usually exorbitant in Europe.

Well it really isn't, it's a substantial detour (about 3h drive) from the coast to Andorra. The main highway between Nice and Barcelona runs along the coast.

Good point, however from Andorra one could easily drive into France (say, to Perpignan) and return the car, then take a train to Barcelona.

Seems like that would work.

The OP doesn't really say anything about timing. With plenty of time, trains might generally work, with car rentals/taxis as needed for certain side trips. But if this is a quick spin through 5 places, I like the idea of renting a car for the first 4 stops and then taking a train to BCN to avoid the hefty drop off fee. In any case, the OP shouldn't need (or want?) a car in Paris or Barcelona, just in-between.

I would take the bus from Barcelona to Andorra. I just did it this summer, there are many busses daily and it is under 3 hours each way. Going to Andorra first before Barcelona won't really save any time unless driving, in which you could probably save a couple hours total.