In reply to Dorte Bjerre Steensgaard:
There are many, many places to stay in that area, although if you're planning to go at a busy time (e.g. Christmas) you should book early...
Given the three zones you plan to climb at maybe the best idea would be to stay somewhere in Arbolí, which is equidistant from both Siurana and La Mussara. This place is highly recommended:
https://www.rockclimbinghouse.com
The owner is a climber (and guide) himself and knows the area intimately.
Pete.