preschool is really about social development more than anything IMO - We did Co-op (Narrows Co-Op) through Bates. They are in Univ Place. We had tried another Co-op prior to that (Lakewood Co-op) through Clover Park.
Co-ops are only as good as the parents who use them. We had a terrible experience at Lakewood and a wonderful experience at Narrows.
However, if I were to go back to Narrows co-op this year, it would have been a totally different expereince. Co-ops work well and if you cant work in the class perhaps a grandparent, aunt or friend could instead. Several parents did that.
The alternative would be to arrange to drop your child at an in home daycare with a loose curriculum to give your child an opportunity for social play and development.
My oldest did Co-op for his last year prior to Kindergarten. Before that, he was in daycare. My 2 and 3 year old do not go to preschool and probably will not until theya re 4. But they are well rounded social adept children and already know anything that would be considered academically necessary for preschool/kindergarten