We've paired a week exchange to Yellowstone with exchanges to both Jackson Hole area - Teton Village actually, loved location almost at back entrance to Grand Teton NP, where we saw moose every day along our drive back and forth) - and something near Glacier NP. Both were excellent, and both parks offer outstanding hiking opportunities. Being near Grand Teton was perfect for our first trip to Yellowstone, because we used a couple of those days to double back into Yellowstone, which is so large and spectacular, IMO more than a week is more than justified. And you can see most of Grand Teton in under a week. But if you'll be using your own week at Timbers regularly (what I would do if I lived on your coast) with ample opportunities to see more of Yellowstone plus Grand Teton, then I'd pick something near Glacier. We've exchanged into both Glacier Wilderness Resort and Meadow Lake, would go back to both, and something in Whitefish could also work.