Apart from NYC, Las Vegas and San Francisco, there aren't really any interesting cities to see in America, they are all a bit identikit. If you are going to the States you may be better off not visiting a city but visting their National Parks which quite frankly are the most spectacular in the world. Yellowstone, Yosemite, Everglades, Bryce, I could go on and on but the Americans got lucky with their natural splendure and they are fantastic at looking after them. Also how about just taking a car around New England in the Fall, you will be there at the perfect time.