We use Apple Tree Children's Center that is on 1st St. next to Bandana's. The have a decent center, with good teacher to child ratios. We have 2 boys, just about to be 3 and 5. For the 5 year old, the preschool program they do is very good. They review letters, numbers, work on spelling their name, and writing to get the kids ready for kindergarten. For my younger son, it is more of a play atmosphere, but still structured and they work on manners and listening skills at that age.
For what we looked at in Ankeny, most of the major centers (La Petite Academy, Tender Years, Child's View) we felt that Apple Tree had the best environment and preschool education. We used to live in Ames and went to the Bright Horizons center at Vet Med, that place was the absolute best that we have ever been to, but the Apple Tree center is pretty good to.
The only issue I would say there is, is that communication sometimes get's lost. There might be a special day, where we need to bring something for our kids and we find out about it the day before. Also, once a child enters kindergarten, Apple Tree does not do before and after school care, so if that is something you might need down the line, it is something to consider.
We choose not to do in-home daycares given that you are at the mercy of that person's schedule, if they take vacation, you have to and if they are sick, you don't have a place to take your kid(s). With a center, they are always open, all year round. But this is all a matter of personal preference.
I would say visit as many places as you can. You will start to get a feel for what you think is good and what is not and then go from there. Also, as I am sure you are aware, get ready for sticker shock on the cost. Daycare is not cheap and if you have another child in daycare at the same time, the costs seem almost astronomical.