The vast majority of US National Parks are amazing spectacles of nature. Some of them, though, are amazing spectacles of lameness.
Number one on the lame list is Cuyahoga Valley National Park in Ohio, a relatively new addition. I don't know what Congress was thinking when they promoted this park all the way from a National Recreation Area to a National Park. Did someone owe someone a favor? There is nothing really wrong with the park if you compare it to a metropark, which is a large regional park in a metro area, usually run by the county. There is something very wrong if you compare it to a National Park. It should be stripped of its title and revert back to a National Recreation Area or it should be given away and made into a metropark for the Cleveland/Akron area.
Number two in lameness is Hot Springs National Park in Arkansas. I would have made this number one, but it has been a National Park for many years. In fact, it was a National Reservation before there was even a Yellowstone National Park or a National Park Service. The park is small and it has virtually no scenery. It is in the middle of a city. It has some fine historic buildings, and it should be converted into a National Historical Park.
Last on my lame list is Petrified Forest National Park in Arizona. I hate to include this park, because it is a fine idea. The trouble is that there is virtually no petrified wood to see. Much of it was dynamited and carted off a hundred years ago. The Blue Mesa is pretty, but darn it, I wanted to see massive quantities of petrified wood. Having I-40 running through the park does not help, either. Perhaps this park should be demoted to a National Monument, but I do not feel strongly about that.
I can think of a few other parks that should have been kept at the National Monument level, but they are fine parks, not lame at all, and I don't begrudge them their higher status.