You've got some great ideas from mom's so far, so i'll just add that maybe you and your son could go to the store to buy a new toy or game or movie as a special treat for him to look forward to.
When I had my tonsills out i remember looking forward to only being able to eat popsicles! lol but i fast figured out that frozen pudding pops felt better on the still sore throat...
I did stay in the hospital after my surgery, i dont know why, but i remember wondering around the next day being really board. so definately take time passers and lots of them! :)
ps- i dont remember if there was bloody drool from tonsils or molars... so taking his pillow may not be best idea... i'd ask dr 1st.
Good Luck, and remember, if you keep your attitude about things positive, ie-"it's a fun adventure to stay in a hospital", he will likely do better, than if you're negative about it! ;)