Your day will be pretty tight if you have to be back in SF by evening. It's easily 2 1/2-3 hours to drive there. And much of the trek is on small roads that go through towns, not on expressways. It's not a trip I would want to undertake after dark when I'm tired. As far as an approach to visiting Yosemite on just one day, you've got two options - the Valley or NOT the Valley. If you go to the Valley, you'll only have time to take the typical tourist shots unless you ignore the landscape and focus on things like macro work or architecture (yes there is man-made architecture at Yosemite, and some of it is photographically interesting). You could also bypass the Valley and drive on up to the Tuolemne Meadows area and take in the lakes and rock formations there. You could even go all the way through to the Tioga Pass entrance (if it's open - may not be due to snow) and down into Lee Vining. I don't know where my 4x5 transparencies of my Sierras trip went - they're in a box somewhere in the house - but there was some spectacular scenery in that high country on the east side of the Sierra. At that point you're just a pebble's toss from Mono Lake, which is worth a visit in its own right. No matter what you do, you'll have some spectacular views to take in.