Get him something practical! Guys like practical things like electronic gadgets, books, stuff for his car, and so on.
Clothes are nice, but get him clothes that he likes, not what you necessarily like, or you wish he's wear.
I have plenty of clothing in the closet from well meaning girlfriends that I never wore. Just saying :-)
You shouldd rent a party bus and invite all his closest friends and take him to his fav restaruanttt. thats why my friend did for her bf
does he have a car? lol or maybe u should plan a romantic fun night out