The hike from the parking area along Tioga Road to the Tuolumne Grove of giant sequoias is an easy hike with a little bit of cardio thrown in to make it worthwhile.
This hike starts at the large parking area 1/2 mile up/north from the Crane Flat gas station (with a decent convenience store) on the west side of Tioga Road. There are a few buildings at the trailhead, and they look to be for some sort of infrastructure. One building obviously had a generator running, and it was still running when I drove by it the next day.
There is a large sign where the trail begins that informs you that this is the old Big Oak Flat Road, and it is indeed still paved for stretches. The route goes around and to the west of a forested knoll, then begins to drop steadily through a forest of red fir and lodgepole pine. It's not a big deal because the AEG on this hike is minimal.
You are already used to walking in the deep dark woods when the first sequoias appear. They're pretty difficult to get good glimpses of because of the other tall trees, but the real treasure is to get closer. Think about trees with 10-20 feet diameters. There were very few sequoia cones on the ground when I visited on July 4, 2012, but that may be due to any number of reasons.
The trail down along the old road hits a junction with a dirt trail branching off to the right after about a mile, and you should definitely take it. The trail hits a gigantic, burned stump after about 50 yards that has a tunnel through it. This trunk is easily 20 feet across, and probably closer to 30. Hike through the tunnel and the trail bends to the left before continuing back to the old road. This area has the most sequoias, and it is very isolated. Turn left onto the main trail and return the way you came by enjoying about 400 feet of elevation gain over a mile-and-change. No big deal.
Remember that it is illegal to leave any trail (the dirt trail I described above that forms the small lasso loop is perfectly legal).