My sister lives less than a mile from there, and we live about 35 minutes from there, so we go often.
There are lots of hotels right there, especially around the perimeter of Gurnee Mills Outlet mall which is right across the street. Baymont Inn looks pretty good from the outside, I've never been inside.
The Jewel food store on Grand Ave. & Hunt Club Rd. has discount tickets if you are interested. Just stop there on the way and save a few bucks. It's about 1/2 mile west of the main entrance.
My sister's kids go to Catholic school and they get out June 7, my kids get out June 10. Great America isn't generally THAT crowded during early June and late August, so you should be ok. Get there early and line up near the double decker carousel for the rope drop. If you like coasters, line up on the LEFT side and head straight for Superman. If you don't get on early, be prepared for a 90 minute wait at the very least, Last time we were there the wait was 2 hours.
My 8 yr. old is rather petite and she can get on a lot of the coasters, so your 9 yr. old should be fine. Their website should have the height restrictions for all rides.
FYI, Great America doesn't charge by age, they charge by height. Therefore, if your young ones are tall for their age, they may be charged the adult price. I think the cutoff for child's admission is around 52", but I'm not positive.
As far as the shows, we always stop to see the one at the Grand Music Hall. Last year it was an ice show which was great! They generally have some kind of musical revue. The almost always have a magic/illusionist show of some kind which is just so-so. The Pictoruim usually has a good IMAX type show which is no extra charge, but at certain times last year they were showing a special Michael Jordan Imax show which was $10 extra. There was never a line for that one.
If you like simulator rides (like Star Tours) don't miss the Space Shuttle ride near the front of the park. Kids generally like that.
Be prepared for expensive food that is not that great. There is a food court there that has a fairly good variety of items. The fried chicken restaurant (Aunt Fannie's??) is not good at all. They served my daughter chicken nuggets that were completely raw inside. When I brought them back they just said oh well, we'll give you more.

Pizza Orleans has pretty good pizza. It's over near Orleans Square.
They have 4 different water rides, but we don't care for Splashwater Falls. You go up a hill, then come right back down. The wait in line isn't worth the short ride. The best bet is the Whitewater Raft ride (like the one in Animal Kingdom).
The log ride is fun too.
My absolute favorite coaster is the Viper in Southwest territory. It's a really smooth, fast wooden coaster. If you like the teacups at the MK, they have the same ride there only they are pottery cups instead of teacups, also in Northwest Territory. By the way, avoid the buffet in Northwest territory too. We know of several people that got ill after eating there.
That's all I can think of right now. Feel free to PM me if you have any more questions. Have a great time!