I would go to Murphys (area). See Mercer Caverns or Moaning Caverns, Calaveras Big Trees, Hike into Natural Bridges swimming hole-nevermind, might run across some nudists there, ha ha. That would scar the kids. Well, hike into Candy Rock Swimming hole then and if there was time, drive up highway 108 towards Sonora Pass. There are a couple spots past Strawberry, CA that are drop dead gorgeous and some neat hikes in there, too. That should get you the Sierra Nevada experience, not quite as fantastic as Yosemite, but a lot of family fun nevertheless.
Source: I grew up near Yosemite