Of all the snakes on the short list, the garters would be the ones that you would see the most and enjoy the viewing of a display tank of due to their diurnal nature, as Tim eluded to the more nocturnal snakes would be hidden most of the time.
You wouldn't necessarily need to have a divided water area, as that would be harder to keep high drinking water quality, instead you could just use a large water bowl with a similar set up to what Tim's picture shows. I have had display set-ups in the past like that for garters and it was a lot of fun to watch them as they can be very active during the day, especially in the mornings.
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Jeff Benfer
gartersnakemorph.com