It's a little on the short side; probably three nights, although I know of plenty of people who have done it in less (I probably won't.)
But I'd like to add a smaller overnighter as an add-on while in the area. So, I resurrected my old "Two Colorado Trips in one" map, and added two more potential hikes to it. What I'm really thinking of most are the Four Pass Loop plus the Castles Route, in the nearby West Elks Wilderness. The Blue Lakes I like, but I think it's both far enough away and big enough of a hike (including lots of elevation gain) so I'll probably do it as part of a different trip with something else in Colorado. I also added the Holy Cross hike, but it has some of the same problems as Blue Lakes, so the Castles Route; an out and back, is the best one to add to the Four pass loop.