I'm from Columbus, Ohio and I mainly frequent two stores: The Train Station and Strete Hobbies.
The former is, as you'd guess, all trains, well stocked, and for the most part has good prices. There is also plenty of help that like to talk and mostly know what they're talking about. Even if they don't, they're still enthusiasitic about it.
Strete's is a classic shop - car, plane, military, etc. models, as well as trains. The owner has been in the same location since the 50's as far as I know. I'd guess his operational style hasn't changed since then either - he hates computers, does everything on paper

. He's not the greatest conversationalist (then neither am I) until you get to know him, but he knows what he is talking about from a huge depth of experience, and is the place to go to get that hard to find part - if he doesn't have it, he knows where to get it (or can tell you when the hard to get part maker died

). Expensive though. Oh, and he is also a
fantastic structure builder / detailer. It's inspiring to see a serious artists work!
No one in my area is strong in DCC, unfortunately.