So when are you coming? Also in South Carolina you can get into the swamps and "black water" w/ the Spanish Moss and get some "lowland" moody shots.

If you are interested in wild life, Yellowstone/Tetons are hard to beat.

A 2 week trip from Yellow Stone to the Grand Canyon would be amazing (w/o an ocean). The landscape and wildlife are simply world class

Timing is somewhat important. The parts of the road around Mt. Rainer are expected to close for the season tomorrow. Same with some of the roads in/around Glacier, Yellow Stone, etc. The key roads into interior of these parks may not fully upon until mid/late June depending on the snow pack.

In the northwest U.S. some of the mountains can get staggering snow fall.

If you are coming in the spring, the seasonal wildflowers can be simply stunning in some areas.

The northwest U.S. (Seattle, Cascades, Mt. Rainier, Oregon coast, etc) is likely the least tourist dense. In general the Southwest is just so darn big, it is hard to get overrun with tourists. Some spots are small and popular and easy access (Zion/Bryce) other of the parks are permit only so there is a very limited number of tourists ("The Wave" is North Coyote Butte - gets all the attention, but South Coyote is just as amazing, less famous and easier to the get permit - I was the only one all day on the butte - get a guide for this one, there are several and ask for a late start to get a lower sun in the sky lighting, etc.)

I suspect you will have a great time no matter where you go.

Happy clicks.

Mike