I rode between Barcelona and a town south of Montpellier in 2003. Getting out of Barcelona was a pain, but once you escape, the riding becomes pretty nice. There are some canals you can ride along in Languedoc, near Narbonne, I think, that connect to Canal Midi.
I recall a long, gentle climb as I approached the French border, but nothing too difficult.
I think the area north of Barcelona is called Costa Brava. There are some pretty ugly hotels and box stores near the coast, but some nice beaches, and it was pretty affordable when I was there. The terrain once you leave the ocean is mostly wooded and pretty lush.
Perpignan and especially Narbonne are charming towns. I didn't get as far as Provence, but the Languedoc is enchanting.