Since you are going up the tram, then you'll be in the State Park Wilderness. You do not have many choices in camping as there are designated camping areas. Basically there is Round Valley and Tamarack Valley. If you go OVER San Jacinto peak, then there is Little Round Valley. The scenery at all of these is good. The hike to Round Valley and Tamarack Valley is easy and short. The hike to Little Round Valley is more challenging as you have to hike up to the peak and then down a little ways on the far side before you camp.
You need to get an overnight permit to camp. The self issue permits at the Long Valley Station near the Tram are for day hiking only during summer. Overnight permits can all be taken during weekends in the summer and not available. You need to call the State Park Ranger office and find out the availability of overnight permits.
Their website is
http://www.parks.ca.gov/?page_id=636
On this webpage, you can get the phone number and you can download maps as well showing the camping areas.
If you go south of the State Park Wilderness, then you enter the Federal Wilderness. From the tram, that involves a decent of about 1000 ft. Usually its easier to come up Devil's Slide Trail if you are camping in the federal wilderness and the permits can be had from the Federal Ranger Office in Idyllwild on the way up (though availability is still an issue). The state park office is also in Idyllwild, so if you are in the area anyway, you can get permits for camping for the State Park Wilderness for future weekends while you are there.
"So we are probably about where this pebble is, 2 inches off the edge of the map."