I've been in the American West a lot. Here is my advice:
Different tools for difference projects. If I was shooting wildlife, I'd want a 300mm zoom. If I was shooting sports, I'd want a minimum of a 200mm zoom and ideally 300mm and it would be fast (i.e.: f2.8). But frankly, I doubt you're shooting either.
What I would argue is critical stuff for anyone shooting landscapes and vistas in the US West would be:
--a damn good tripod. No cheap POS. Get something that is rock solid stable, even on rough uneven ground. If you're going to be hiking, then get something that is probably good for hikes (lightweight yet still stable, folds up small so probably 3 joints rather than 2, probably composite material).
--filters. Specifically a neutral density filter (when you want to blur the waterfall or stream during the day). A graduated neutral density filter (when you want to shoot a sunset). A circular polarizer filter when you want to make the clouds pop and also deal with the harsh sun that will cause glare.
--a remote shutter exposure (cable or microwave) to minimize rocking the camera when you click the shutter.
--microfibre cloths b/c it's dusty out there.
Don't get me wrong--I love me a good 200mm (or longer). But when I've been out in the West, I wasn't using a 200mm (or if I was, I was shooting at a wider angle and not 200mm). I was using wide angle lens mostly.
I've attached a couple of examples of some of the stuff I've shot (all of which were done with shorter focal lengths or did not require a zoom)...first one required a tripod and NDF and was shot at Estes Park, second one was shot in Fairbanks Alaska and gives you an idea of the "white nights" during the summer, next is the Columbia River Gorge, then Juneau Alaska with a mix of fog and sun, Garden of the Gods in Colorado, and Wahkeena Falls off of the Columbia River. I've got others from other locations I could post but some are too big or not appropriate for this site. The point is, I will use a 200mm or 300mm a lot but rarely when I'm shooting out west unless it involves wildlife that won't come to me or wildlife (like Bison) that I prefer to keep some distance with.