The best one my children (girls 11 & 8) have ever gone to is called Catholic & Cool Kids camp at the Bishop Lane retreat center in Rockford, there are a couple sessions throughout the summer it is a good introduction to overnoght camp as it is only for 1 or 2 nights and it is right there in Rockford, another camp I sent my 11 yr old daughter to last summer was called Camp Ondesonk, it is in Ozark Illinois lasted for 1 week and she had a BLAST!!!! this was a little far and she did get homesick at first but ended up having the time of her life!! Also, the girl scouts and the cub scouts have some awesome summer adventures--check those out, I know my 11 yr old will be attending a few of those this summer. Hope this helps!
D. Smith