Well if you are trying to get from Girona to Barcelona, consider doing it by way of St. Felieu, and then along the coastal highway.

I just LOVE Brittany, to me its one of France's best kept secrets. The best seafood I have ever eaten was in Brittany. I also love Catalunya. I am so jealeous, it sounds like you have an amazing trip planned. But bring your climbing gears! It also sounds like a touring bike is in order if you are trying to cart luggage around. A bike like an older steel terry classic or madeleine would be great, and not expensive (you can find them on the buy/sell a used terry site). FYI the terry isis/symetry does take tires as wide as 28mm and accepts a rear rack, so that can also work for credit card touring.

A PRP is fine too. While not marketed as a touring bike, I did tour on mine and it did accept tires up to 1.4" wide if I recall which even worked on packed dirt roads in chiapis. Get the folding rack though (and it only accepts a rear rack, but if you go new they can make it for you with a front rack but that increases the weight cuz they have to use heavier tubing in the fork). One thing I liked touring with a friday was how easy it was to combine it with other forms of transportation. Need to take a bus, fold it up and they are more likely to let you bring it on board than a full size bike (and not charge you extra to do so).