Went to Andorra a couple of years ago for a walking holiday with my wife.
Had a great time - stayed in Soldeu which is a good centre for walking.
Try out the spa in Andorra la Vella it is very relaxing, the main town is a bit built up, but it opens up as you get higher up in the mountains.
Andorra is also good for jeep safari's we went one one and had a great day in very remote mountains - whole villages where no one lives any more - shepherds who do not see any people for several days - very wild.