There are alot of really nice drives in OC...
My personal favorites
PCH - Pacific Coast Highway
HWY 74 - From San Juan Capistrano to Riverside Has several nice overlooks of the entirty of lake elsinor
HWY 2 - Through Wrightwood and Mountain High over to Palmdale
HWY 38 and 18 - Through Big Bear and Arrowhead Lakes, Very Very nice in the Springtime. Lots of twisties. Take I-10 out to Redlands, and get on HWY 38 and follow up the offical "Scenic Biway" through Big Bear Lake, or take the HWY 18 to circle the lake. Nice Drive. Just watch for the Troopers in the reduced speed zones of Big Bear. They will often pull you over just for having too laud exhaust so that they can can check to see what else they can give you a ticket for. Beware the 35 MPH zones, you will want to speed because the street is absurdly wide, but it's not worth it. Anywayz. Hope my ideas have helped. See you out there!