My baby won't be 3 'til next year, but I've taught preschool off-and-on for...good God!...17 years!!!! I've taught at several different types of schools, but the kind I'd most recommend - especially for "Mothering" mamas - is a co-op.
* There's a lot of parental involvement, both in the classroom and in running the school. This can be tough if you work, but it's so worth the effort! You will really know your child's teacher, what's going on in the classroom, who his/her friends are, how he/she behaves and interacts, what he/she likes and responds to at school... You will also make a lot of friends with kids the same age as yours and feel part of a warm, child-focused community. Every family who makes the effort to be involved in a co-op has a similar willingness to sacrifice their time to focus on their kids. As a result, you often have families from very diverse socioeconomic levels and racial/religious/political backgrounds, who find a genuine common ground at the co-op. It's great for the adults and the kids.
* The academic philosophy is "learning through play" - in every sense of the phrase. On the one hand, it really is learning, not run-through-the-classroom-willy-nilly. The available activities are very consciously chosen to be stimulating and challenging to young children on a variety of developmental levels and to address gross and fine motor, literacy, math, problem-solving, social, artistic and musical skills every day. But at the same time, you won't see kids sitting at tables doing worksheets, to impress adults with the vision of 3-year-olds "working on a 1st grade level". (They can do that in 1st grade! They're only 3 once!)
* The price is very low, since the school is entirely run - and cleaned! - by parent volunteers and only the teachers are paid. This also means that after teacher salaries and renting space, extra money from tuition and fundraisers can all go toward teaching materials. So well-run schools that have been around for awhile usually have fabulous educational toys, solid libraries, good gross motor equipment and ample art/craft supplies, compared to similarly-priced programs...and even programs that charge much more.
I could extoll the virtues of co-ops all day, if anyone wants to PM me.