As others said, this is a wide open question and then some.
Personally, if it were me taking the trip and I had no real time limits, I would at least consider something like the following:
New Orleans -- a thoroughly fascinating city
GSM NP/Blue Ridge Parkway/Shenandoah NP
Maybe a side trip to Washington, DC, where one could easily spend a month visiting museums etc.
Knoebels amusement park, Elysburg PA (because I really like it)
Letchworth SP in New York; maybe also Watkins Glen, or a few others. They have some very nice parks. Letchworth is extra special, though.
Niagara falls, particularly if one hasn't been there before.
Cross through the Adirondacks and Vermont (lovely country all) and see some of the White Mountains of New Hampshire
Bar Harbor, ME and Acadia NP
On the way back, I might take a somewhat more costal route and see some of the eastern seabord cities: Boston, NYC, Philly, etc. They are fascinating to visit but not much fun at all to drive in or even near. There are some superb things to see and do in smaller burgs, as well; for example, the Mystic Seaport boat museum.
