DW and I just returned from a trip to Fallingwater, Niagara Falls, the Finger Lakes region and Letchworth State Park. Thanks to the above posters for their suggestions. Two weeks wasn't long enough to cover everything but we got a lot in.
On the way to western PA we drove through the heart of WV, stopping to see the New River Gorge and the high bridge crossing it. Amazing! Near Fallingwater is Kentuck Knob, another FLW-designed home which we enjoyed almost as much, as well as the nearby state park and its waterfalls. We stayed at a B&B about 20 minutes away (it's in the middle of nowhere).
We had never been to Niagara and it's just stunning, although the tacky development nearby reminds me of the beach what with the go-karts, wax museums, etc. We stayed at the Marriott Fallsview with a two-story room with loft overlooking the falls, which cost an arm and a leg but was worth the experience, especially at night when they light the falls with colored lights.
From there we went to Seneca Falls where DW especially enjoyed the women's rights museum, as did I. Another B&B, very nice. I love B&Bs although this one was like staying in a museum. We didn't have a comfortable place to sit for almost two weeks, except for the Marriott.
From there we went to Watkins Glen via Ithaca, where we ate at Moosewood (a wee but disappointing but worth it). At lunch there we overheard someone talking about the Cornell Dairy Bar where ice cream from the Food Sciences school is sold. With help of Google we easily found it, and wow! that was the best ice cream I ever ate.
Hiking the Glen was an experience not to be missed. We stayed at a B&B-style hotel which also had no comfortable chairs. Very cute, though, but the experience was somewhat lessened by the snarky owner. I learned to ignore him, though.
Finally we stayed at Letchworth. Very scenic, as others have said.
Thanks again. We had a great time, but we hugged our La-Z-Boys as soon as we got home.