I highly recommend Mark Holstad at Nature's Balance. A couple of years ago he found a small-ish bullsnake in our basement when he was helping us with a mouse problem. He (the snake) apparently followed the mice in when he was a baby, and was living off of them in our house (nice, eh?). When Mark brought the snake out he asked if I wanted him to take it up to Loveland and release it away from homes. I said I thought they were harmless and I was fine with him just putting it out in the yard. He told me that they are very hard to get rid of, and if it set up house under our front porch we would have a hard time getting rid of them, as they will find their way back unless you take them a long ways off.

He has handled a couple of other things for me at a building I have been doing facilities work for as well (squirrels, wasps, voles), and is very
thorough, reliable, and will explain the options carefully if you have specific concerns (ie: spraying, etc).
-Lynne