Oh picking a snake is always fun! I got one of our female ball pythons for Mother's Day last year (I'm hoping for another snake this year...hint..hint...to hubby and kids LOL)
Maybe have your boyfriend go through some of the forum threads and galleries to view some of the excellent pictures of various snakes people here have. Then you can research the ones he liked best to see if it suits what he would like in a snake as far as husbandry, handling, size at maturity, etc. For example, my husband Mike likes the albino milksnake our daughter has, however, his very large hands make handling her not that much fun for him as well as he prefers a slower moving, heavier bodied snake...so for Mike a milksnake isn't a preferred gift idea.
Black milksnakes though are a neat snake. They start out tri-colored and then turn a beautiful black over time (one of the only snakes that changes color completely as an adult). They are the largest of the milks and one of the few snakes where the male exceeds the female in size.
So many choices....have fun and let us know what you end up going with.
~~Jo~~