I've never actually driven it, but have ridden the N-260 many times: It's known as the"eje Pirenaico" or Pyrenean axis, and runs from Sabiñánigo in the west, to the Med coast. Gotta be one of the best biking roads in the world. You might end up on it anyway if you are (wisely) going to avoid the motorway down to Perpignan.
All of the big cols are great when crossing into Spain, Bielsa, Portillon, etc.
If you're returning the same way, I recommend driving up the cañon de Añisclo, between Escalona and Fanlo. It's one way, running northwest, so takes you out of your way going down there. However, avoid it in or after heavy rain, as that's when there tend to be a lot of falling rocks.