In reply to Marti999:
The Picos is a magnificent area of superb, rough limestone, one of the great mountain ranges of Europe. There is good climbing in the central and the western massifs (mainly on Pena Santa), with some routes as long as 700 metres. There is a network of huts (refugios), which tend to be friendly, clean, and offering good food at reasonable rates. The weather is, like many mountain areas, variable. Autumn can be more settled than summer, though the last two summers have been very good. (2011 was a washout.) Often you get inversions, with cloud and rain in the valleys with sun higher up. The two main jumping off points are Los Lagos/Covadonga for the western massif, and Potes/Fuente De (where there is a cable car) for the central.
Dividing the two massifs is the stupendous Cares Gorge. Starting from there is not advisable, as you would have to slog up about 1600 metres to get to the start of routes. Robin Walker's Cicerone guide is a good introduction but is very out of date: it was written in 1989. More modern Spanish guides and topos will be available in outdoor shops in Cangas de Onis (the town nearest the western massif) and Potes.
The most famous peak is the iconic Naranjo de Bulnes (also known as Picu Uriellu). This can get very busy, especially on its normal route (mainly dif/v diff with a little MVS). It also has harder big wall routes. However, there are many other worthwhile objectives.
NB: The Picos is also one of the most important caving areas in the world, with at least five systems deeper than 1,000 metres, including the Sistema Xitu/Cueva Culiembro - a 1264 metre deep, 15km long through trip explored by Oxford University Cave Club and the Cave Diving Group.
Post edited at 08:23