If you head up that way yourself, note that the USGS 15 minute quadrangle maps (Blackcap and Huntington) and older editions of the Sierra National Forest map are incomplete. They don't show the best access to the Three Sisters. Drive the paved road to Trapper Springs campground (8550 ft), on the west side of the reservoir, almost all the way to where Cliff Creek meets Courtright (8330 ft). There is a well maintained trail up to Cliff Lake (9520 ft). From there, about one mile of easy cross country takes you to the 10620 foot summit. The rocks furthest to the southeast and closest to Cliff Lake are the tallest of the three peaks.
Considering that it's not a very tall mountain, the view was astounding. To the north, we had great vistas of the Clark range and the Ritter range. (I hadn't realized quite how far north Three Sisters is.) To the east, we could see beyond Goddard, all the way to Mount Tom and Mount Humphreys. To the south, we saw down into the astonishing gorge of the Middle Fork of the Kings River, and beyond it to the Kaweahs and Mineral King.
It was fun hiking on the west side again. I hadn't been there in a while. The moist west side has a greater variety of conifers than the drier east, more of a forest understory, and none of the pungent sagebrush smells of the east. The lower angled west side trails made for pleasureable walking in light duty trail shoes.
We took four and one half hours to reach the summit and three and one half to return to the trailhead. We weren't exactly burning up the mountain. You could climb Three Sisters faster.
Three Sisters ... the peak climb with the Motown chorus:
Hey, babe, take a walk on the west side. And the Sisters all sing: Hey boop, bedoop, bedoop, bedoopidoop doo!
Richard L Hoesly adds:
Why didn't you mention the mosquitoes. I was up there with my family on the next day. We hiked in from the trail head to the southeast. We were planning to stay the week but left after 1 day because we were getting eaten alive. My 10 year old daughter, young sweet meat, counted 96 bites on here arms and face the day we got back home. Other than that it sure is a pretty area.