hi K.,
I recently have been researching preschools for my 2 year old son.... my advice is you are going to have to narrow a few down and then tour the facility and talk to the teachers, etc. It really is the feeling you get when you walk into the preschool if it is the right fit for your child. We really liked Brush Creek Montessori in Santa Rosa, (they give tours every 2nd Wednesday of the month), but if you want a really structured environment, a Montessori school might not be the best for your child. Some preschools also have a waiting list. We also really liked Mt. Taylor on Slater Street in Santa Rosa, they spent a good 45 minutes with us talking about the school and our needs, etc. Many of the preschools have websites that give some good information and I also read many parent reviews on preschools in SR from yahoo.
Good luck!