If Tom hadn't said something about how nice it was I might never have done that one either. Looks not that spectacular on the maps and it certainly is not in the heart of the rest of the parks peaks...
I've hiked into the Monarch Divide area...well, let's count how many times:
1980 [with a friend, 4 days, up to Granite Lake and Granite Pass area]
1990 [solo, 4 days, to Kid Lakes]
1991 [Sierra Club, 9 days, over Kennedy Pass to Volcanic Lakes and Glacier Lakes]
1995 [SC as leader, crossed the Monarch Divide hiking from South Lake to Roads End]
1997 [SC as leader, over Kennedy Pass to Volcanic Lakes to Kid Lakes]
2001 [with a friend, 3 days, to Grizzly Lakes]
2001 [SC as leader, over Harrington Pass to Swamp Lakes to West Kennedy Lake and out over Kennedy Pass]
2006 [solo, overnight to Tent Meadow]
2006 [SC as leader, over Granite Pass to Glacier Lakes to Kid Lakes]
So, 9 separate trips. That's a non-trivial percentage of my total Sierra backpacking experience. Obviously, something keeps pulling me back there.
For me, part of it is those trips in 1980 and 1990. The former was one of my first backpacking trips ever, and I was just awestruck at the scenery. We were woefully underprepared (college students--say no more) and had a near-death experience, but I fell in love with the Monarch Divide anyway. I can still picture the view from Granite Pass after a mid-September afternoon snowstorm, with every crag and crevice on the Black Divide etched in snow.
The latter was part of a vacation I took the summer after my wife and I split up--part of the healing process, in other words--and one of my first trips after a long period of not backpacking. It was also my first serious foray into off-trail hiking (we went a little ways off the trail in 1980), and I lucked into a) a really elegant route and b) a breathtakingly beautiful lake basin.
So my fondness for the Monarch Divide stems party from personal history. At the same time, it really is an amazing (and apparently underrated) area.