I'd put a little more thought into it than pick a city off of a map. The bike facilities might be lousy.. I'd research locations for beauty and bike infrastructure and what kind of cycling the area offers.. You are a roadie touring type.. And what kind of terrain appeals to you is the most important question.. The coastline of California, the mountains of Colorado , or maybe the beauty of the desert in Arizona or Utah..
Did you Google magazines such as Bicycling to see if their on line additions have some available articles about favorite cycling destinations.. Other source might be Adventure Cycling since they sell maps dealing with bicycle touring telling of their favorite routes..