We did the day trip through Extranomical Tours from San Francisco. It’s a very long day since Yosemite is about 4 hours away. We were picked up at 6:30am and were dropped off at 9:45pm (we also had about 40 people on our bus for dropoff). Having said that, though, be ready to pick your jaw up off of the floor throughout the day. If you have a high-end camera, you’ll be thankful you did. Yosemite is breathtaking. From the mountains, to the valleys, to the waterfalls, to the wildlife, it’s an unforgettable experience and one you will not regret taking even considering how long the day is. Note that you’ll do a lot of walking on this tour, but how much you walk will be up to you. We took advantage and climbed the rocks up to the waterfall and took some amazing pictures. If you can spare a day while in SF, and either already did Napa or aren’t interested in Napa, take the trip to Yosemite. You won’t regret it.