Distance: 7.8 miles (12.5 km) round trip to Dewey Point;
9.2 miles (14.7 km) for Dewey Point plus Crocker Point;
10.5 miles (16.8 km) for Dewey, Crocker, and Stanford Points
Elevation at trailhead: 6,900 feet (2,100 meters)
Dewey Point Elevation: 7,200 feet (2,200 meters)
Crocker Point Elevation: 7,100 feet (2,160 meters)
Stanford Point Elevation: 6,659 feet (2,030 meters)
This trail serves double duty as the McGurk Meadow trail, which is important not just because you'll be passing through McGurk Meadow en route to Dewey Point, but because the roadside sign marking the trailhead mentions McGurk Meadow but omits Dewey Point.
There's no parking lot at the trailhead, but you can find parking along the road's north shoulder a few hundred meters east of the trailhead. If you reach the turnoff for Bridalveil Creek Campground, you've gone about a quarter mile too far east; the trailhead is at the top of the hill you just came down.
After hiking north for about 2 miles (3 km), you'll merge with the Pohono Trail. Turn left to go to Dewey Point. Going right will take you, if you're ambitious enough, to Taft Point, Sentinel Dome, and Glacier Point. It's much shorter to visit them from their official trailheads, but if you do hike to them from here, it's 9.2 miles (14.8 km) round trip to Taft Point, 13.4 miles (21.6 km) round trip to Sentinel Dome, and 15.4 miles (24.8 km) round trip to Glacier Point.
The trail is largely flat, with only about 300 feet (90 meters) of elevation change from the trailhead to Dewey Point, but you'll descend 500 feet (150 meters) in the last mile and a half or so from Dewey Point to Stanford Point. If you're allergic to uphills and the prospect of reclimbing those 500 feet doesn't enthuse you, see if you can get someone to pick you up at the tunnel view, where this trail ultimately ends. It's actually slightly shorter (9.7 miles/15.6 km vs. 10.5 miles/16.8 km) to hike one way to the tunnel view than to hike round trip to Stanford Point, and it's downhill all the way from Stanford Point to the tunnel view.