I have a bright 3.5 year old girl who has always been very verbally advanced(letter sounds by 1.5, early reading at two, some spelling at two, making up elaborate stories, ryhmes, jokes, at two, using very sophisticated language now at three and reading much better. Her memory is frightening). She is also quite bright with puzzles, shapes, and numbers ... is a very very high energy, spirited, bossy, chatty little girl.
TwinkleToes ... I feel like you could be writing about my dd (now 5.5). She and your daughter share so many of the same qualities (reading at two, early math, amazing memory) -- right down to the May birthday!
I do not have the perspective of some of these parents of older children, but I can share my experience of having dd in kindergarten right now.
Unlike many others, I did not have a great experience with a play-based preschool, but I think that was more due to a poor fit between dd and her teacher. DD also did not find any of the other children in the class to be stimulating as playmates and that prompted her (in her "spirited" kind of way) to find other ways to keep her brain occupied ... which got her into trouble almost daily.
I was really worried that dd was getting the wrong message about school. Even at the age of three. That she would think school wasn't fun. Or that she was "bad" at it. Or a behavior problem. So I pulled her out.
We are lucky enough to live near a gifted private school and we were able to enroll her there. To me, the best part about the preschool experience at the gifted school was how deeply they delved into their units of study (and dd gobbled up every fact), how busy they kept the kids (no time to get into mischief) and the peer group. She is still there now in kindergarten, and is able to subject accelerate in math and reading, all while staying a kindergartner. I, too, worried about her maturity when it came to skipping a grade. This seems like the best of both worlds.
You say you live in an upper middle class district. Are there any gifted schools there? Have you had any experience with other gifted kids in your area? I would imagine they are out there. I've had luck finding some at science camps, or special library programs with science-y topics that appeal to my dd. Even if those kids are quite older than your dd, their parents can provide invaluable information.
Good luck!