I've been to a smattering of National Parks and Monuments.
>Rocky Mountain National ParkThe frontcountry can get moderately crowded, but there is a lot of good hiking in RMNP, and the crowds feel less lolly-gaggy than what you'll find up in Yellowstone because there's not much to really gawk at. People come here to hike.
>Sequoia & Kings Canyon National ParkI only spent less than half a day here looking at the big trees. Cool place. Not sure what else it has.
>Yosemite National ParkThe frontcountry is full of lollygaggers, but the backcountry is amazing. The only problem is that even people who go into the backcountry will feed the bears (I saw it happen), so bears are major pests here that will bother you whether you're camping or not.
>Yellowstone National ParkThe frontcountry is full of lollygaggers, but the backcountry is supposed to be deserted. I've only been in the frontcountry here, myself. Someday, I'll do a backcountry hike among the grizzlies and bison.
>Grand Teton National ParkExcellent mountain climbing opportunities here, although it does get relatively crowded, even in the backcountry. Your best bet to avoid crowds is to get high and do a traverse.
>Glacier National ParkThe Going-to-the-Sun Road is terrifying to drive on. You might *actually* shit your pants. As
>>428648 suggested with his pic, fishing on the Flathead is excellent, which is what I did when I went. Lots of bears and moose too.
>Zion National ParkReally beautiful desert valley, with some world-class views either right from your car or from a short day hike. From November-March, the park gets relatively low traffic. In the summer, they close the upper canyon to cars and you have to rely on a shuttle. Someday I need to go back and hit the backcountry.
>Mount Rainier National ParkYou can climb a mountain with actual glaciers here. Use extreme caution, and hire a guide if you don't have any experience doing this. You could get into serious danger without the right training.
