Yeah, I agree that you don't really need a triple. I doubt your locale is as hilly as where I live, and I get by with a 39 tooth chainring as the small ring on a double. You could go with a 36 or a 34 if you really need it. For additional reference, I also have a couple of touring bikes, and unless I'm fully loaded and/or going up a very steep hill, I almost never use the smallest ring on the triple. It's nice to know it's there, but I wouldn't plan your purchase around it.
Do look for something with a relatively long wheelbase, clearance for wide tires and fenders, fender mounts, and rear rack mounts at the very least. Most importantly, find something that fits, and that doesn't show signs of damage (bent fork/tubes, excessive rust, etc.). It's a good idea to bring some basic tools and ensure the seatpost and stem aren't stuck.
Good luck!