I concur with Bob West, the Rock Creek area is extremely scenic. Its about 5+ miles from the SnoPark up a mild grade to the Little Lakes Valley, but the view would be worth the effort. Rock Creek Lake makes a good intermediate turnaround at about 3 miles if you're breaking fresh trail or running out of daylight, or just plain tired.
Just snowshoeing around the Mammoth Lakes can be a nice outing. They keep the road plowed to the Tamarack XC ski lodge. Parking on the road is limited and from there you can follow unplowed roads to the various lakes.
