Sand boas are awesome, though a couple I worked with were rather nasty little buggers. They can be really fun, though.

Ball pythons are of course a good way to go, and are relatively easy to maintain as long as you can keep proper humidity.

I also have a soft spot for milk snakes. I think they are just all around awesome snakes, and I highly recommend them for first snakes. They're very easy to take care of, and usually very easy to feed. They're extremely gentle...in fact, I can actually hand-feed more than one of my milk snakes. I have one that only has one eye (genetic), and he will take the fuzzy out of my hand like a dog. Great animals.

Rainbow boas are fantastic, as well, and I would also suggest looking into Irian Jaya carpets.

Good luck