Where should we go? Where should we avoid?

My husband flies often and he has lots of free airline tickets to use as he wishes. We have been to most of the big cities in the US. Now he thinks we should visit smaller cities for weekend getaways. I'm afraid that smaller cities we haven't seen yet might be boring, so I'm hesitant to use up tickets trying this. Please, do you have suggestions about really fun small cities we might visit? And could you also tell us which small cities just aren't much fun? I think Savannah might be a good town to see, for example, but I don't know what we would find in Indianapolis...