We love Story Land!
We've had the best luck at the Red Apple Inn. Meals aren't included, but it is VERY family-friendly and budget-friendly. There's a pool and a swingset /play area in the back, and a common room where you can eat takeout meals and snacks. They do have some kind of breakfast included with the room, but it's very bare-bones-- tea bags, instant oatmeal, individual boxes of cereal, things like that. We got takeout from the German restaurant next door at their sister (more grownup-oriented) inn one night, and ordered a pizza another night. There's also a restaurant called Glen Junction that I personally can't stand (greasy low-quality food), but it has this electric train that goes around the ceiling as you eat that a lot of kids love. We stayed somewhere else last year, because my parents and sister wanted to come along, so my dad booked a family cabin, and honestly it just wasn't worth the money in my opinion. There are higher-end places, too, but I don't think we could afford those-- Red Apple is basically a very nice motel.
Your best bet is to plan on two days at Story Land, and 2-3 nights in the area total unless there's a lot more you want to see. On the first day, go after 3pm, and you get the second day free. Then on the second day go early with your free admission and stay until you're done seeing everything you want to see. Again, coming from a more NFL perspective, the food inside the park is low-quality and greasy, so we brought healthy snacks with us. I actually do a grocery run at Trader Joe's or Whole Foods (or both) before I go, and get things like pita bread, hummus, natural peanut butter, and yogurt.
A lot of the other "kid" things in the area are more for older kids. This year, we're going to tack on a visit to Santa's Village as well; this will be the first time I've done this since I was a kid myself. But I wouldn't take a 3 and 5 year old to, say, the Attitash slide or anything like that.
Hope this helps!