SirMolay:

With 8-12 hours I'd still say go to the south rim of the GC, take the shuttle to the stops and view it, maybe do a short foray down one of the trails. It involves the least drive time and seeing it will certainly make you want to come back and hike in it. There'll still be lots of people there, but not as bad as mid-summer, same with the temps -- better than mid-summer, too.
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- kevon

(avatar: raptor, Lake Dillon)