The massive North Dome is like having a little bit of Tuolumne right in the Valley... or right above the Valley... and... well, I think the rock quality is better than Tuolumne too, but I can only speak for Crest Jewel. Expect a possibly long approach and descent, sun all day, possible high winds, and fantastic views down Valley and across at Half Dome.
The two sensible approaches are to climb Royal Arches or to approach from HW 120 at the Porcupine Creek Trailhead. The former requires a lot of climbing, the latter requires 5 miles of relatively level hiking.
Royal Arches: After finishing the climbing and gaining the trail into the woods, scramble up some steep steps to a large boulder at a level area. Move around behind this boulder and pick up a good trail that heads due east along the top of the Royal Arches wall. Eventually this trail crosses some slabs and the views of North Dome tempt one to scramble directly up to it. Resist and continue into the woods until directly below North Dome and above the Washington Column. At this saddle, and just before dropping down the other side, the trail branches off up towards North Dome and past a bunch of cool boulder and obvious bivy spots. Continue into the woods on a good trail until reaching the base of the dome. Some climbs start straight ahead, others up and around the left flank.
Porcupine Creek Trailhead: Follow the trail into the woods due north until almost reaching the back (and top) of North Dome. Cross the major trail that heads west (Yosemite Falls Trail) and pick up a smaller, but well traveled, trail that winds down around the west side of North Dome. Eventually this trail falls apart and you have the choice of keeping near North Dome (possibly heinous bushwacking) or continuing well west to reach a passage down through massive, steep slabs. I've only gone down these slabs (as a descent from North Dome) and they turned out to be quite easy, but I was left in doubt as to whether they'd be passible (and whether or not I was going the right way at all) until the very end.
This route is surprisingly good. Reid’s book only gives it one star, but most people who have climbed it consider a hidden gem. You’ll encounter solid rock decorated with slabs, face, cracks, corners, chimneys, no fixed gear, exposure and amazing views of Half Dome the entire way. Although rated 5.7 there are some thought proving sections. Personally, I felt that the 5.7 rating was a sandbag and you could easily argue that some sections are closer to 5.9. Climb it for yourself and decide. ...[more]Browse More Classics in CA
More info on the North Dome Gully Descent: Walk north along the top of the dome looking for a trail that eventually heads west. Follow this trail down hill heading slightly away from the dome. If you lose the trail (which I found likely) you will have serious bush whacking good times. Eventually break east crossing the slabs that were seen during the approach. Continue down the slabs until you reach the trail on top of Royal Arches. Follow this trail east going up and over Washington’s Column. At one point you will have an easy class 2 descent on a sandy 2 foot ledge with a significant drop to the right. Soon after, the trail seems to dead end. If you’ve reached this point, back track a little. Go up hill a bit and cross a steep slope. Continue east for another half mile to a mile. Looking to the right you will eventually see the decent through the sandy boulder field. Follow this down to the valley floor. One of the major problems I found with this decent are the numerous trails that begin and end. From the top of North Dome to the Valley floor is likely 4 hours for someone who has not done the decent before. Here are a few tips to help you through this. First, keep in mind that there are no rappels necessary, so if you are thinking about setting one up just keep on going. Secondly, if you go to the east side of Glacier Point Apron (near Grack) and look across you should see the decent. This will help you understand how far from Washington’s Column the gully is. Lastly, doing this in the dark for the first time could have some serious negative side effects. I saw several bivy sites on top of Washington’s Column that are likely from climbers who have decided to wait until morning before heading down. If in doubt, pack a space blanket and lighter to start a fire and hunker down.
Unless you are wanting more pitches to climb (e.g. Royal Arches linkup) or you are staying in the Valley and the time for driving up Hwy 120 is too unappealing, for any route on this dome I don't see why people don't just hike in and out from Hwy 120.
Coming in, it was a nice and scenic hike on an easy trail, and it only took me 2.5 Mammoth Brewery IPAs to reach the summit (about 2.5 hrs, including stops for pictures and giving hikers & trailrunners beta), and heading back after sunset, even with the 1,500' gain and seeing how long I could go without a headlamp, it was moderate enough of a grade that I made it in barely over 2 hrs (faster time probably due to the fact that I had no more beers to sip, although I was texting while hiking).
I don't think it unreasonable to assume 30-45 min to approach any route on North Dome from the summit as long as you don't get lost.
So in light of that, apart from the exceptions first listed, I don't see why more people don't take this approach! Easy hiking, faster, beer-a-hike-able while passing other hikers (can even cache on the summit, and check out Indian Rock & the cool arch on the way in or out) and you can return in the dark without having to be familiar with the N Dome Gully descent or hiking forever down the Yosemite Falls Trail.
Just park at the second 'vista' pullout after Porcupine Flats and bring your contour/trail maps. Also, enjoy the historic Hywy 120 along the way.