Begin your walk on the right branch of the Rockefeller Loop (a very pleasant family hike in its own. The full loop can only be hiked in the summer and fall. The Bull Creek loop consists of two trails: the Bull Creek Flats Trail on the south side of the creek and the Big Tree Trail on the north.
At the western end the two are joined by an automobile bridge, but at their eastern end is only a seasonal footbridge that's normally installed between mid-May (but sometimes not until the end of July) and late September. At other times the creek may still be only a few inches deep and easily forded. When the footbridge is out and the creek becomes a raging torrent, the best alternative to the full loop hike is an out-and-back on the Bull Creek Flats Trail, which is the better of the two trails.
Directions to trailhead: From the north-central part of the Avenue of the Giants, four miles north of the park visitor center and just south of the hamlet of Redcrest, turn west on Mattole Road and drive 1.5 miles to the parking area for the Rockefeller Forest Loop Trail. (If you want to make this a one-way hike and make car shuttle arrangements, a second trailhead is located at the Big Trees Parking Area, another three miles west on Mattole Road.)
Yes there is parking at the Big Trees Area by Rockefeller Grove...