As far as freshwater goes, the Aviarium has the best selection I've seen. They usually have odd ball stuff with decent prices. They'll give the reef club discount for fresh too.
I'm sure that most of the stores sell both FW and SW supplies but maybe not both livestock. Every store that I have been into sells supplies for both. You could hit up the sponsor map and see what stores would be easiest to visit on your trip through. Call them up and ask over the phone if they carry both (or to what degree).