Love the San Jacintos and San Gabriels. I am sure you could piece together a good loop. You could also hike on the PCT but it would probably require a car shuttle (with a few exceptions I am sure).
If you camp at Little Jimmy (it's on the PCT) as was mentioned above, watch out for bears...it's been notorious in the past.
If you go to Silverwood Lake, be prepared to potentially run into a good number of people, many might be in boats in the lake but it get's a good amount of use (at least the PCT section does).
After the snow melts, Big Bear offers quite a few options to come off the PCT back into town so you wouldn't have to have a car shuttle, just drive to Big Bear, park your car somewhere appropriate and get a taxi to a trail head (yes there are taxis that do this) or hitch a ride. If you do park on National Forest land be award that they require an Adventure Pass (I know you can get one at the Big Bear Discovery Center which can also give you trail condition updates).