It's difficult to advise you on planning your route without knowing what sort of ride you'd like it to be. You'll be crossing the Pyrenees. There is, therefore, the opportunity to do some of the most famous, beautiful and very tough climbs. I would certainly be doing that if I were making this trip.
However, suffering on big climbs isn't everyone's idea of fun, and I wouldn't recommend the Tourmalet, for example, to those who weren't reasonably confident of their fitness. So you might want to think about how strenuous you want your trip to be, and then plot a route across the Pyrenees accordingly.
It's a very beautiful partof the world, you'll have a great time. I'll be cycling in the Pyrenees myself next year, can't wait.