Re: What to do in Dayton
Air Force museum is free too, which no one has mentioned. Also make sure to check out the presidential hanger if that's still open to the public (pretty sure it is). They have old presidential aircraft in a couple large hangers and some other cool/interesting aircraft. It's actually on the base (not with the rest of the museum), so you might need to call ahead of time to see if you can even see it or what that might involve.
Canal Street Tavern usually has good music and is right across the street from the Dragons stadium as already mentioned.
Dayton Mall and the Greene are both short drives away from downtown (10~15 mins) if you are into doing the shopping thing.