There are a lot of different classifications of public land, but the major US federal ones are National Monuments, which can be natural or man made, are generally pretty small and packed with tourists year-round, National Parks, which are always natural, larger, quite impressive and full of tourists in the summer, and finally National Forests, which are huge, beautiful, but not nearly so touristy. National Forests are managed land, and many have a sustainable amount of logging, mining, and recreation going on. Generally they're open to hiking and backcountry camping, but don't provide much in the way of tourist support. IMO the best places to truly get away from it all, if a little less spectacular.
As far as the best the US has, I'll second those apparent opposites: our park system and the internet.
