I drove Going-to-the-Sun the first weekend it was open that year - in 2009 that wasn't until July 4th, so if you want to drive the whole thing it may be a little later in summer, which means that the crowds are worse, but ah well. I don't think the number of people there really detracted from my experience, but I had also just come from the hoards of people in Yellowstone and Glacier seemed practically vacant by comparison. Like at Yellowstone, seeing a mountain goat and her kid would have resulted in a way bigger traffic jam than this one.
Yosemite is really high on my bucket list - I still haven't been and the pictures are amazing. Just need to have vacation days and money at the same time!