There are four standard routes up Baldy. I'm with Alan in that my favorite is the Northern approach, but I usually drive to the ridge top trailhead instead of going up Acorn Canyon from Wrightwood. I've listed the four basic routes below along with some map links with points plotted on them. You can also go totally XC up San Antonio Ridge and various other hard core routes, but I list only the four standard routes.
1. Devil's Backbone A = trailhead in Manker Flats. B = Baldy Notch which can be arived at either via the service road or the ski lift. C = the Devil's backbone. D = summit of Mt. San Antonio (A.K.A. Mt. Baldy).
2. Ski Hut Trail (A.K.A. Baldy Bowl Trail). A = trailhead in Manker Flats (same as route 1). B = point where you turn off of service road. C = the Sierra Club hut (sometimes open, sometimes locked). D = the ridge you traverse to from the hut. E = summit of Mt. San Antonio (A.K.A. Mt. Baldy).
3. Mt. Baldy Trail (A.K.A. Bear Flat Trail, A.K.A. "Baldy from the Village" trail, A.K.A. Bear Canyon Trail). A = Ranger Station in Baldy Village. B = Bear Flat. C = "hard scrabble" (loose rock) area of trail (along much of the ridge). D = summit of Mt. San Antonio (A.K.A. Mt. Baldy).
4. "Other Devil's Backbone" route (A.K.A. "Baldy from the North" route). A = "Overacheiver's" Trailhead in Wrightwood. Note that there are parking restrictions on Acorn Canyon and that you can't park at the end of the road. You can park in the vicinity of the intersection of Finch and Acorn Canyon. B = Point where the trail from Acorn Canyon summits Blue Ridge. C = Primary trailhead on Blue Ridge Road. Note that Blue Ridge Road is subject to seasonal closure. D = Pine Mtn. E = Dawson Peak. F = Dawson - Baldy Saddle, the "saddle of despair" (you lose a lot of elevation between Dawson and Baldy all of which must be regained in order to summit Baldy. You also have to re-climb Dawson on your way back. Though this is a shorter route than from the village, some consider this to be the most challenging of the four routes, particularly if you start from Wrightwood. The northern route is cross country (although there is a use trail) from Dawson - Baldy saddle to the summit. G = summit of Mt. San Antonio (A.K.A. Mt. Baldy).
