Hey Nate,
If you are interested in keeping ringneck snakes at all I'd suggest you go with southern ringneck snakes, I've kept 6 of the 12 U.S. sub-species of ringneck (though I don't think they consider there to be sub-species anymore?). Out of those 6 the southern ringneck snake was the easiest kept, a 10 gallon tank, a substrate of eco earth/moss/mulch, a clear water bowl that's big enough for a couple snakes to be in at the same time, and a bunch of hiding spots (flat rocks, pieces of bark), and the snakes will do more than fine. A good idea for a hidespot is a 6"X6"X3" rubbermaid/gladware container (the disposable plastic ones from wal mart, etc.), with a little bit of the substrate and also moistened moss, keep the lid on but cut out a circle in the middle for a entrance point... And bury the container into the substrate so the snake feels like it's going underground to hide. (Ringnecks need to feel very secure and at home to feed in captivity) One downfall to ringnecks is they tend to dry up quickly, but this container will prevent that, the snakes may hide outside of the container but if it gets too dry for them they'll end up there.

Southern ringnecks have the most variable diet out of any ringnecks I ever had, one group (3-5 adults) I had in a 10 gallon tank with the setup I described above thrived for years and eggs were laid several times. But out of this group on any given day of the week they would eat earthworms, tree frogs, salamanders, small snakes, anoles, skinks, even live day old pinkies were taken, it was also keeping this group that I saw how often southern ringnecks swim to try and catch fish. A water bowl filled with guppies would often times lead to the whole group swimming around in the bowl trying to catch the guppies, just like garter snakes.

Southerns are also one of the smallest "sub-species" there's a couple populations were adults will be full grown at 8"-9", I'd say on average they're about 11", and I've had a couple over the years that were near 15". Ringnecks in general can live long, and can thrive in captivity for as long as you can meet their never-ending needs. I had one 22" regal ringneck snake for 3 years, and I know of a guy in AZ who caught an adult regal 20 years ago and still has it, so that snake has to be at least 25 years old. Regardless of their size their musk is pretty bad, and they aren't really a snake you can hold, though they may tolerate it a little. I've never seen a ringneck bite a person, but in my group setting of southern ringnecks one snake bit another snake on the neck, and the snake that was bit on the neck died later that night. Not sure if southerns have venomous saliva like the regals or if the bite just punctured the snake's windpipe and caused it's death? Who knows. But ringnecks are in no way dangerous to people.

They're a cool snake if kept right. And despite being nocturnal they may still cruise through the enclosure at any time of day, whether or not they'll run and hide when they see you is a different story and depends mainly on the specimen...
I currently don't have any ringnecks, but would keep them again if I could get my hands on another albino or some regals.