Hello Peter. I agree with Lisa-the trip to Glacier Point is worth the drive (weather permitting). I was up there in October last year for sunrise and it gave me the goosebumps it was so beautiful, notwithstanding it was ~25 degrees F in the morning. My question to you is how much time you want to spend in your car? Yosemite is an amazing place, so you might want to spend your time on and around the valley floor checking it out. As Lisa stated, the east side of the park over Tioga pass is spectacular, but a good 1.5 hour drive from the valley. If you decide to do this, keep going over Tioga to Lee Vining and fit in a shoot at Mono Lake as well as the fall color in Lee Vining Canyon (and other adjacent canyons too, including June Lake Loop). However, that is a big agenda for two days and tires me out just thinking about it. I am going up to the Eastern Sierra in a week for the fall foilage, so I will post again after I get back if something jumps out at me. Have a great trip and enjoy Yosemite.
David