The Picos De Europa, easy access from Santander or from Bilbao. If you enjoy walkint there is always the Camino de Santiago, although it's about 25 days long - goes from the French border to the cathedral of Santiago de Compostela in Galicia.

There is a Lonely Planet guide book which deals exclusively with walking in Spain.

I'll second the Picos. It's a good few years since we there, but from what I remember it's best to buy your walking maps before you - decent maps were few and far between over there. Could be something to do with the fact that walking hasn't really caught on as a pastime in Spain, and anyone who wants to explore the mountains does it by car, or by hiring a place in a 4x4.

If you want a bit of luxury, there's a parador at - I think - Fuente De. But there are also bars and inns with rooms, and if you stop at one which serves the gloriously strong blue cheese they make there, it makes for a great ending to a walk.

Potes is a good gateway, but busy - a bit like Ambleside in relation to our Lake District.

As for the Camino de Santiago, I don't think it's compulsory to walk all of of it, unless you want your official certificate signed at the end. I'm sure no one would notice if you only did as much or as little as you wanted.

Hi,you might like to consider the "Cabo de Gata" in Andalucia,may be good if you want tranquility and the beach/coast not far away.John.

Super walking on Mallorca particularly based at Puerto Soller or Puerto Pollensa, we have been for the last four years and try to add a new walk each year.
If you are interested buy Walk Mallorca from http://www.walking.demon.co.uk to see what is available. best time to go Oct or Feb.

Good luck wherever you wander,

Dave

Still thinking about it so I can't tell you what the walking is like from experience but a friend and I are looking seriously at a trip to Andalucia combining a city break in Grenada with walking in the nearby Sierra Nevada now that it's possible to get decently priced direct flights to Grenada from the UK. The walking looks good and because it's a ski area we're trying to find out if the chair lifts still operate in the summer for the benefit of walkers like they do in the Alps. Takes so much of the effort out of it!

Sm