I just got back from Yosemite Valley. The after visiting the Eastside at the begining of the month with mixed results I found the valley alive with color. Starting at the Arch Rock entrance the Broad Leaf Maple trees are glowing. Up through the Merced canyon, all along South side drive, especially pretty just east of Cathedral rocks, into Illilouette canyon, and up the Mist trail to Vernal falls the trees are a bright yellow/Gold. I would not normally stop at the bridge to take a shot of Vernal falls but right now would be a great time to do so as the Maples are colorful from the bridge all the way to the falls(get there prior to the sun coming up or after the sun is behind Glacier Point).
There are a couple of Aspens in the Yosemite Lodge area that have turned and make a good frame for shoting the falls. The Black Oak trees dont look like they have started to change yet nor the Dogwoods that I saw.
P.S. I t was dark when I drove by, but I have heard that Lee Vining cayon has turned and is looking nice right now.