Thanks for the nerite snail anecdotes. I think the suggestion of sticking to the smaller horned versions is a great one and I'll go hunting for one this weekend.
@Salty: Unfortunately I find myself working 7 days a week most of the time, so this isn't a big issue. I did go out of town for thanksgiving, and there was no problem over a 3-day weekend but I'm not sure I would want to do that often. My tank at home has an automatic feeder that I use on holidays, and I may buy one to use here if I decide to leave town over christmas.
I'm a little concerned about temperature, but so far it hasn't been a problem. During the day they keep our office about 25, and at night/weekends it drops to 22. Even with the lights off, the tank seems to average at least a degree above the ambient temperature. I think 23 is pushing it for these fish, but as long as it doesn't go lower I hope they don't mind. If it seems to become a problem I have a 25w heater that I can put in, but I'm hoping to avoid it.