Are any of the "Nerds" movies PG? Eleven year olds usually like the corny stuff!
Percy Jackson and the Lightning Thief. Rated PG, my 11 year old son just finished watching it. Synopsis - Fantasy adventure where teenager Percy discovers he's actually a demigod, the son of Poseidon, and he must master his newfound skills and find Zeus' stolen lightning in order to prevent a war between the Greek gods.
"Stand By Me" might be a good one. I don't recall anything too adult in it. It does share the comradery of young boys. Might want to check the rating though.
. . . How about Men in Black?