From San Diego, you can drive up I5 to LA, then drive up 101 to Santa Cruz. You will get some Pacific ocean views along the way. If you don't waste any time lallygagging, you can be in Santa Cruz in about 7 hours from San Diego (assuming not much traffic or weather delays). Big Basin Redwoods state park is very close to Santa Cruz. See
http://www.parks.ca.gov/?page_id=540 If you spend a day there, you can be back in Santa Cruz that night, then spend the rest of your time driving back down highway 1 through some great scenery and part of the time on 101. If you like wine or enjoyed the movie Sideways, Santa Ynez valley is about halfway from Santa Cruz to LA. Not much scenic between LA and San Diego unless you enjoy city sights. Best scenery north from Malibu along PCH, or north of Ventura / Santa Barbara area. This makes for a lot of driving and a tight, rushed schedule
Very likely crappy weather - lots of rain expected this winter. We just finished a solid week of rain, with more coming. February can be extremely wet, so you might want to have some backup plans. Summer tires won't be very good in Big Basin, so make sure the tires are good below 40°