RMNP and Arches both have timed entry which has made for a more pleasant visitor experience recently, though it's a gamble to try to plan a trip through it in case you don't secure an entry time. My last time through Arches, on the V7 in September, I didn't have a timed entry but luckily was able to talk my way in.


If any of you have read Edward Abbey's "Desert Solitaire," he was complaining about too many visitors at Arches when he worked there back in the 1950s... Moab was also too busy for his liking. At that time, Arches didn't have paved roads, which kept a lot of folks out. He did have some interesting ideas though and not just complaints, such as a big parking lot outside the park, no *new* roads in the park, and maintain the existing roads strictly for staff, shuttle, and bicycle use. That has, to some extent (during busy season), been successfully implemented in Zion National Park.
When I visit GSMNP, the most visited of the parks, I tend to take that approach. Ditch the vehicle, travel by foot. It's around 71 miles on the Appalachian Trail to walk in one end of the park and out the other and IMO, if you're able to, that's the best way to experience it. GSMNP has historical legal reasons why it can't restrict access or charge for entry, so timed entry wouldn't be possible there.