For years it seemed like the trail up to Castle Dome was the only one in the Park, judging from the amount of traffic it had, at least on weekends. For some reason, the thought of driving up to a trailhead that appeared to be almost halfway to your destination made the rest of the journey seem like... well, a "walk in the Park". For anyone who has hiked up to the Dome from the campground, however, it's a different story — you're pooped before you even get up to the trailhead.
At left is probably the most "influential" trail sign in the Park. Only a few hundred yards from the Kettlebelly Ridge parking area, it will pretty much determine just how serious you (and your party) are about "seeing the Crags". It will definitely determine if those kids you brought along for a "little hike" are able to sustain their early enthusiasm for the Great Outdoors. If you veer to the right, you'll end up at Root Creek in less than an hour, with cool shade almost the entire way and even cooler water in the creek. If you take the fork to the Dome, you've got 2 more hours (and 3½ miles) of steep, sunny hiking ahead of you, but with a reward at the end worthy of your efforts.
Continuing up to the Dome, you'll soon be reminded of the mechanics of a "switchback". Initially, it seems like a good idea. Instead of climbing straight up the steep hillside, you zig-zag back and forth, ending up at the upper location with a little bit more distance but at a lesser grade. Sounds too good to be true, eh?
On the plus side, this part of the trail, though fairly steep and south-facing, has good tree cover. At one point, though, after laboring along at a snail's pace for a good distance, the grade began to diminish imperceptively, and I took this as a sign to "shift into second gear", as it were. After loping along at this pace for awhile, when the trail actually did drop back to being level-ish just before the junction to Indian Springs, I felt as though I'd forgotten how to walk properly. It was as if the entire evolution of mankind was being played out in just a few hundred yards — beginning much like an ape must have looked as I shuffled along, staring at the ground, one foot barely ahead of the other, then s-l-o-w-l-y rising to an erect posture as the grade levelled off and my pace quickened into a much more efficient stride. The only element absent was, of course, the theme music from "2001: A Space Odyssey"...
The Indian Springs junction is at about the halfway point to the Dome, and the 5 minute side trip to the springs should be mandatory on a hot day. Nice views open up to the south and southeast and it's the last water you're going to see all day, so enjoy it.
Above here is where the trail eliminates "the weak among us". Mercifully on the shady side of the rocks, the trees soon go bye-bye and routefinding is brought to the forefront as the trail becomes faint at times, but by looking ahead you shouldn't have much trouble. If you go "off route" up here you'll know it. Just below the saddle behind the Dome the "trail" splits up into many smaller (and more manzanita-choked) sections, but if you want to climb the Dome, work your way to the right, and if you're looking for a picnic spot with a view, bear to the left.
If I remember correctly, the easiest way to the top is to scramble up to the brushy right-leaning ramp, then continue around to the right (east) side, go behind one of the big flakes, and follow a ladder-like quartz dike the rest of the way. The views are as expected. Don't dilly-dally up here if it looks like a thunderstorm is forming, unless you want to do the Ben Franklin thing — I've seen lightning strike the top of the Dome several times. It's about 2 knee-crunching hours back to the parking area from this spot.