OOB is very odd. Or at least I find it that way. During the summer, the population swells to (I think this is it) almost 200,000 at a time! Other than that, it is 9,000. That might be wrong though, I'll check. Anyway, during the fall, winter, and most of spring, it is completely closed up and desolate. A few bars are open, but other than that, its very quiet. The highschool is not very nice either if you ask me. It is a large barn with a few add ons. The pluses of living there would be it is quiet, a lot of parks (espiecially Memorial Park downtown, which is beautiful), decent schools (again, I don't like the highschool but mostly because of how it looks

). But it is also VERY crammed in.
Scarborough is quite suburban. It is very spread out, but never really becomes "rural," just always single family homes spread apart. It is not pedestrian friendly at all. There are a lot of houses going up though I think. The highschool is superb though. Very, very, focused on academics from what I have heard. I think the math program there is highly praised. Anyways, Scarborough would be good if you like suburban living and having to drive to get anywhere.
I might be biased because I live there, but I think Saco is your best bet. Lots of new houses going up, good schools, GREAT highschool, where I go now (Thornton Academy). There are new houses going up around the intown area, where you can walk to places for groceries and even a few restaurants downtown. Across the bridge is Biddeford, if you want to dine out. There are quite a few athletic programs too, for your children to play in. Pedestrian friendly, not too busy. Parts are suburban, parts are rural, parts are a little more city-ish (but not really like a city, just for the area). The one complaint I have about Saco is the lack of parks. The city took down one across from my house, and the two only basketball courts. The police virtually banned skateboarding. So if your kids like skateboarding or outdoor basketball, that wouldn't work. Overall though, Saco is your best bet!