Muir as a side trip after Whitney--on dayclimbs or overnighters--is very common in my crowd. Like Steve's estimate, it should add 30 - 45 minutes. At my age now, though, for me it has to be an overnighter.
Some of my Flickr albums contain pictures, route lines, and comments on difficulty, etc. Some albums are more useful than others. Here's a sample:
Mt. Muir. Others can be located in
my albums and doing a search on "Muir," for example.
Some climbers and the popular guidebooks describe the route as exposed class 3, and some insist it is at least class 4. I've certainly retrieved a lot of rappel slings left behind up there.
Looking down at my companion in the wedge Snacking Bear describes:
