Ken: FYI, from the main entrance the nearby campsites like Poverty Flat (3.9 miles), Los Cruzeros (6 miles), etc. are on a quota and you get assigned campsites on a first come first served basis. Poverty Flat has one group site, but I know it's already reserved for the 3rd weekend in March because I was looking at that weekend for another trip, which I ended up reserving in April.
Per Jay's suggestion, coming in from the Hunting Hollow entrance to Coit Lake is a way to go without any reservation or quota. I think that's about a 10 mile hike. The hike from the main entrance to Mississippi Lake is 12 miles. That would make a good overnight too.
Per Lisa's suggestion the Orestimba Wilderness would be a great trip, but would be more than an overnight.
Not sure if I can go or not (probably not - little league opening ceremonies that weekend for my son), but I would think a 12 miler to Mississippi Lake from the main entrance or to Coit Lake from Hunting Hollow would be good choices for one night. Two nights at Mississippi Lake would give options to day hike into Orestimba.