Getting my two cents in on this thread late but if you want another suggestion, check out the Rapid City SD area, black hills, Mt Rushmore, etc. There's a lot more to do there than you'd think. And if you are a motorcyclist, it's heaven. If you aren't (or even if you are but hate dirtbag bikers), make sure to time your trip when the Sturgis rally is NOT happening. Late summer/early Fall is ideal, the whole area is virtually deserted and the weather is perfect.
Another nice place is the coast of Maine. Fly into Portland, rent yourself a car (or bike) and stick to Highway 1 heading north. When your vacation is half over, turn around and head back. Play it by ear and sleep where you end up each night. Awesome.
Eric.