I've just ridden SF to SD. Its about 670 miles and as an intro ride it's great!

You get to říde through big cities, (LA) forests, (Big Sur) coastal towns (Santa Cruz), it has it all.

As a huge bonus for first timers there are plenty of pockets of urban settlements so restrooms, bikeshops, resatsursnts, hotels and csmpsites are never far.

This site lists some nice pointers S.D. to S.F. ? by Bike | San Diego Reader

But I'll point out Google maps using bicycle mode gives a great route free of major highways they encountered and the phone coverage (ATT) in big Sur was okay.

One more thing. The town's can be quite dense so you can ride 50 miles a day or one hundred.

Now to ride back!