As you've discovered, Palo Alto is a small city and not one that dominates escort advertising.  Presumably you are looking for an escort to come to you on outcall.  That being the case, I'd recommend that you use area codes for your search.  Palo Alto is in 650, but is very near the border of 408.  A tertiary possibility is 415 (San Francisco proper).   If you focus your search on the 650 and 408 area codes, you will find a plethora of ladies likely to meet your needs.