Depending on where you live, chipmunk identification is either dead easy (for most of the eastern USA, the only chipmunk you might see would be an eastern chipmunk), or very very tricky. Yosemite is one of the very very tricky locations -- there are nine species of chipmunk living in the California part of the Sierra Nevada. Apparently the recommended scientific method for confirming chipmunk species identification is to look at the penis bone. This, for obvious reasons, is not usually practical for photographic identification.
My best guess is that the chipmunk in the first two photos here (taken at White Wolf Lodge) is a lodgepole chipmunk. The others (taken at Mariposa Grove) I think are long-eared chipmunks.
Lodgepole(?) chipmunk at White Wolf Lodge
Long-eared(?) chipmunk in the sun at Mariposa Grove
The chase around the log game
Selected prints available in my
Yosemite portfolio on Redbubble.