If your schedule will allow and you would be interested in participating, a co-op can be a fabulous experience, and also be considerably cheaper than conventional preschools. I looked at two co-ops at the time, and there were significant differences. I think the nature of coops will lead to more variation than you night find in conventional preschools, and I think there are several in the DC area (or at least there used to be).
My kids (now grown) went to Glenbrook Co-operative Nursery School, which was a play-based program in Bethesda. The teachers at the time were wonderful. The help from the parents not only kept the student-to-adult ratio low, but meant that you could see your child interacting in a school setting, and really get to know the teachers, other kids, and their parents. It was a very supportive community.
I haven’t kept in touch, so I’m sure that there have been many changes, but the school has actually been around since the 40s (long before my kids attended in the early 2000s). Here’s the website:
https://glenbrookschool.org/about/