Bodie's the best state park in the USA, by far. No reason to visit any others to know this.
In the area, just north of Bridgeport, is Chemung Mine, a 2wd trip in summer, not sure what shape the well-graded road is currently but the mine's been there a long time so it should be there still.

Click
here for larger photoWhile you're at it, check out the ruins at Masonic, which is the northern point of a triangle between Chemung-Masonic-Bodie. There's not much left there but you did ask for ghost towns. A good ghost town web site is
here. Turn the volume down when you visit that web site, the MIDI is way too loud.
I haven't been to Cerro Gordo in Inyo County (east of Owens Lake) but I hear that's worth the trip, too. It's on the list.