It's pretty much like Rick (Cazador)had said, there will be individual snakes that prefer more handling time then others. As an example, I have two male Oregon Redspotteds (T.s.concinnus)....one is a complete wacko! If I walk past the cage, he just goes balistic trying to hide or "escape" me. Removing him from his tank for cleaning is....well let's call it an adventure.
My other male is the complete opposite and often will climb out of the tank and into my hands and is even content enough to just "hang out" around or on me while I clean the tank out. One thing I can definitely recomend is to get captive bred animals. These should be more used to human contact and not be as flighty, but this is not a guarentee. Garters are active snakes, which means they always seem to be on the go and are not as prone to just curling up and hanging out like ratsnakes and kingsnakes.
Best bet is to get a nice captive bred animal, set it up in a nice sized cage that allows it plenty of room to "roam" and set it up nice and dynamic (with lots of hides, branches, plastic plants, ect), so that the snake has lots to "do" in the tank. I've found that snakes with well done tanks tend to handle nicer, 'cause they feel comfortable in their captive environment. When it comes right down to it though, snakes don't "tame", they're not like dogs or cats....they may habitualize to be handled and see it as a time to "get out" some, but that's really about it. I have some snakes now that I've had for over 15yrs. that are still kind of "wild".
Roy