you will be wanting an early start - reasons being: go while it is cool, beat the crowds that start about 9, and finish the long day at a reasonable time.
For me, the best option was Curry Village. Don't wait for the shuttle buses to take you from there to the Happy Isles trailhead. Just start at 4:30-5:00 am, take a bit of a shortcut, not on the road, but through the tent-cabin city of Curry. You can get to the trailhead in the predawn purple light and have the place to yourself.
Here is what I wrote at the time:
Yosemite Religious Experience 2001
The pilgrim moved reverently through the predawn night, his way lighted only by pure white from the goddess of the night. On either side, immense stone pillars vaulted toward the limitless ceiling. Faint traces of incense lingered in the still air. Ahead, the altar drew him closer and closer. So near, yet so far away.
A religious experience? Yes, but not in man-made cathedral, but a 4:30 AM start from 4000-ft Yosemite Valley floor to the top of 9000-ft Half Dome and back. This was my third trip to the top of Half Dome. The climb always ends up with the last 500 feet of ascent on 55 degree granite using fixed steel cables, but this time it was the early start of this third climb that was so awe-inspiring. I was there by myself, and started early enough to literally have the entire National Park to myself. Not a sound was heard at that hour, no people, no cars, not even birds chirping.
The dark forest path was lit dimly by the moon, the soaring granite walls took on a different meaning in that light, and the faint vanilla fragrance of the Jeffry pines filled the air. I could not believe that I really did have this busy place to myself, coming up the most popular section of the trail. On the first trip in 1993, we had come from Tenaya Lake north approach on a two-day backpacking trip. Then in 1996, we had come from Glacier Point and the east approach. Both of these routes were longer, but with fewer people. On this third time, I expected the Mist Trail lower section to be crammed with people like it usually is, at least for an hour or two, until reality turns most of then back. But I had only seen it like this during the day. What a difference a predawn start makes. The route is 17 miles round trip, with 5000 feet up, and 5000 feet down. A long 11.5 hours round trip. But worth every step. Toward the top, a fellow traveler finally did catch up with me. We had lots of things to talk about, and ended up sharing the top together as well as the descent. Coming down, we were met by the usual hordes of tourists of various nationalities and skills, having fun predicting which ones would make it to the top or not. But we didn't linger too long. I had misplaced my iodine tablets to restock my water supply. The two liters I took were long gone during our one-hour lunch break on the summit. So while my friend stopped off at Nevada Falls to sightsee, I continued on down to below Vernal Falls where there was safe water. So I drank from the spigot, and was transformed back into a lowly, plain tourist.
