Picture books is my vote for what to bring. Surgery every THREE days???!!!!???? Good grief, he'll be groggy from one to the next, not to mention pain meds.... Maybe later on the books.... a cuddly stuffed huggy toy, personalized just for him, maybe a name tag...... type trip. I really have a hard time seeing little kids in pain.... He probably will have blurred memories of the whole thing. Good Luck.