I guess I should answer too. Sorry, this'll be long.
DD1 did go to preschool, but that the time, we were not planning to homeschool. Her first year was at a play-based cooperative that met 3x/week for 2.25 hours. I was in the classroom 2-3 times per month, and the adult:child ratio was fantastic (5 adults to 19 kids). The teacher was wonderful with the kids, and amazingly supportive of the parents too. It was a great experience for me. I had time to get to know all of her classmates as individuals, and all of their moms, as well as several dads too.
DD loved it. As a newly turned 3 year old, she was still mostly engaging in parallel play, but she did seem to enjoy being around the other kids. She got to do a lot of neat things that we don't do at home. I don't set up the easel every day. I don't have a sand/rice/water tub out every day. I don't have paste and glue and glitter out every day. I don't have simple science experiments set up every day. We don't have a play kitchen and at the time we didn't have many dress up clothes (that has changed!). We don't go on a nature walk every day (nature was one of her teacher's favorite topics). I just don't have the time, energy, or inclination, and I refuse to feel bad about it.
(I also don't think any hs'ing parent should feel obligated to provide those things, but DD sure did enjoy them!)
Looking back now as a fully committed hs'ing parent, our coop still gets a great big
from me. If we still lived there, I'd have no qualms about signing DD2 up next year. And as an aside, I've since met several hs'ing families who also belong to coop preschools.
But we moved, and the only option was a traditional play-based preschool: 3x/week, 2.5 hours. DD1 really wanted to go, so she did. The teachers are wonderful, but it just isn't the same as a coop. I didn't feel as involved in what was going on in the classroom, and that doesn't sit well with me. The sessions were a little more structured than I preferred, and I felt the kids didn't get outside to the playground for long enough. There wasn't as much exuberant exploration going on, but it was still very much play-based. It did give me some time to focus on my little one, which was nice.
So now I'm conflicted about DD2. She remembers the preschool and its playground, and has informed me that she wants to go to preschool like her big sister did. But I'm not so sure about it. On the other hand, it would be great to have some quiet(er) time to focus on my 1st grader.
Tentatively, I'm thinking we'll enroll her, but we won't feel bad about taking her out if for any reason we're not comfy with how things are going. I may look at some 1 day/week alternatives as well. And we might do preschool for just one year, because once she's 4, she'll be old enough to participate in some of our local homeschooling activities with her big sister. Or by the time enrollment rolls around, maybe I'll have changed my mind and decided to keep her home instead. How's that for indecision?
*sigh* If there was a good coop preschool nearby, I'd be a lot happier!