Soller is a great base for walking in the Sierra de Tramontana. A good introduction are the 15 walks described in the 'Soller Walking between the sea and the mountains' walking guide plus topographic map. For more walk ideas and detail have a look at the superb 1:25000 scale Mallorca Tramuntana Central Map and Hiking Guide. For accomodation we stayed at the Pension Casa Margarita at 3 C. Reial, very friendly and great value for money.