If you are arriving to Yosemite from the greater San Francisco area, be sure to take Hwy 120 into the park through Groveland, CA. Put the following tag into your GPS to take Old Priest Grade road and save 10 minutes on your drive time. After you reach this point, put in Yosemite Village to continue on.
After that, here are all the best sites to see on your way into the park!
1) Tuolume Grove of Giant Sequoias
2) Drive to Tuolumne Meadows (3-4 hour total side detour)
Tuolumne Meadows is a beautiful and secluded part of Yosemite National Park full of meadows, granite domes, and snowfields. The road will bring you up to 10,500 feet of elevation. If you have time, you could add in the hike to Lembert Dome, assuming the snow isn't too deep.
3) Cascade Creek
This one is literally right off the road, so definitely worth stopping
4) Bridalveil Falls hike on your way in...it's short, but really nice.
5) Tunnel View
Fun side note: With incredible caution, walk the small sidewalk .25 miles uphill through the tunnel. On your right, you will find an air vent tunnel that pops out on the side of a cliff. This will give you a beautiful view all to yourself. Be sure to take your headlamps and use extreme caution in the tunnel. The traffic will be heavy and loud, but all worth it.
6) Fern Springs
Stop here at Fern Springs. This water bubbles up out of the ground and park geologists aren't even sure where the water comes from or how many years it's been underground. You can use your water filter and drink from it. It is as fresh of water as you can find anywhere.
7) One more! This one isn't on your way in necessarily, but if you show up too early and traffic is still bad, you can drive through Tunnel View and hike this instead of waiting on traffic.
If you arrive to the park after the Wilderness Permit office closes, simply go straight to backpacker's camp. Be sure to attach a printed confirmation of your wilderness permit to your tent. It is best to hang this with a piece of string or whichever method you come up with. A ranger may walk by (although rare) just to ensure everyone there has a wilderness permit.