I, too, have a young family and moved to Andover less than a year ago. I agree with one of the prior posts that you can't go wrong any where in Andover. But I do believe you have to look at what;s important for you. There are alot of tucked away family friendly neighborhood where your child, when they are of age, are able to play outside/ in the street, while being watched.
I think some of the things to consider within Andover are: so you want to be close to town, to 93/495, in a remote area? I think you certainly have a range to choose from in andover. All the elementary schools are great so i would not base the house you choose on this.
The Discover Preschool is also a very family friendly PreSchool, although I have heard great things about alot of the PreK's in town.
good luck with your search!