Outdoor/sporty stuff rather than indoor electrical stuff is a winner if you want big boxes (skateboard/football/goal/ramp etc) but tbh at 11 he is old enough to understand that its not the size of the parcel that counts!
My 8 yo wants a DS and realises that even if DP & I both contribute and his dad gets him the games/case he won't get anything else. However, that's what he wants and he knows its expensive, so he won't mind it being a little box.
I tend to thing that big presents are for little children and vice versa!