A loop through the Medicine Bow, Neversummer, Rabbit Ears and Park Ranges of northern Colorado--all the way through the mountains around North Park (the valley in which Walden is situated). Admittedly this was on horseback, but my parents and I did variations on this route this every summer while I was growing up. I've been back to hike parts of it and it is just as spectacular as I remembered! Some of the sections, such as the western part of the Rabbit Ears range) are probably a bit easier now (we had to do a lot of cross-country and spent 3 days finding the route the first time) because it's part of the Continental Divide Trail. On the other hand, the trail through the northern section of the Medicine Bows (from Mountain Home, WY to Ute Pass, where the scenery starts) was already discontinued in the 1950's, so by now is probably a distant memory.

The other true "Great One" was a 9-day trip through the Glacier Peak wilderness of Washington starting from the Upper Chiwawa River: Spider Meadow, Lyman Lake, Cloudy Pass, Suiattle Pass, Image Lake, Canyon Lake, Buck Creek Pass and back to the Chiwawa 2 miles from the starting point (this was with a small group so we had 2 cars to shuttle).

Lots of great day hikes, too numerous to mention.