Good Trails to Ride in SoCal?

I was wondering if anyone can refer me to some decent places to ride. I live in North Orange County, so I'm looking for something you can make a day trip out of. We usually go up to Arrowhead / Big Bear & really enjoy it. I'm not into just going out to the Desert & being around a bunch of squids, e.g. Apple Valley, Lucerne, Johnson Valley...etc. I've contemplated going down to Corral Canyon, but I'm concerned it's really not worth the drive in both size & difficulty. I'm a competent, solid, mid-level rider. So I like some challenges & fun stuff, but at the same time I'm not looking for the anything too crazy cuz my girlfriend goes out & rides with me quite a bit too. A weekend trip up to Kennedy Meadows would be fun, but it's just too far unless we're going to dedicate a couple days to it. I just didn't know if there were any places with decent trail networks in a closer proximity to us.