...My biggest "nature let down" is Yellowstone. I refuse to even go there anymore during June, July or August. It's worse than Disneyland. You can literally get stuck in a traffic jam for an hour. Old Faithful had probably 10,000 people watching it erupt when I was there a few years ago. It's the most mis-managed national park in the country in my opinion. Not entirely their fault - it just can't handle the volume of visitors, even despite its size.
I have the exact opposite opinion about Yellowstone. To me, Yellowstone is nature on crack. The mountains, broad valleys, wildlife, thermal features, rivers and waterfalls, etc. Pure nature to the n'th degree. Here's how I found "nature" there. Backpacked in the northwest corner of YNP, in Montana. In two days we saw one other hiker on the trail. We passed a backcountry campsite about three miles before getting to ours and found these nice grizzly claw scratches on a tree supporting the food pole. That's what we call an attention-getter.
We did another two-day backpack to Heart Lake about a week after the rangers had re-opened the area to backpacking. It had been closed because a grizzly was coming into campsites and pawing at tents.
Another tidbit about Yellowstone is that the Thoroughfare ranger cabin in the southeast corner of the park is the most remote residence in the lower 48 states....at least 30 miles in any direction to the nearest road.
Go to Old Faithful before 7am, or after 7pm, and you'll be amazed how few people are there. The pretty light at those hours goes without saying.
Yeah, bear jams and bison jams often clog the roads. When you're in a bad jam, pull over if possible, get out and enjoy the scenery. Not always possible, but often it is. When you're stuck in a jam and can't get out, smile and remind yourself you're in YNP, not Detroit.
The place is 2.2 million acres......with a little (very little) effort, it's easy to lose the crowds and find nature.
About Mt Washington: I'm appalled at the crowds and commerce at the summit. And every time I'm there, I suspend my righteous indignation long enough to buy some chili and Coca Cola, fill my water bottles, use the clean flush toilets, use the trash cans to dump the trash from my pack, and look at the pretty girls. Then when it's time to leave and I start hiking down, I resume my pure nature-loving state of mind, and bemoan that awful retched summit and everything it stands for.