Welcome To Bike Forums, SemperFiV12!
I live here in NorCal. I don't really think that having a carbon framed bike as your main trusty steed for both commuting and leisurely exercise, would be such a good idea. You have to think about the utility aspect, as well as the short errand aspect, of your bicycle possession.
You might want to go to the grocery store to do your weekly shopping. Perhaps you may just want to pick up a gallon of milk or orange juice. I mean what would you do? ...Perhaps you'd just like to go to the library or the movies. What would you do? At some point you're going to need a rack with panniers. You also have to consider the fact that you're also going to have to park and lock your bike up in some very questionable places. I would never jeopardize damaging or losing my bike under those circumstances. That would just be plain irresponsible.
Therefore, I guess what I'm really saying here, is that you need a well-equipped commuter/utility beater bike first, before any of those beautiful Cannondales.
If you're a NorCal resident, I would suggest that you join the Bike Kitchen, a bicycle co-op, in San Francisco. You might be lucky enough to find just the right frame to build upon, right there at the co-op. Alternatively, you can purchase a frame online. You can then build and customize your beater commuter/utility bike, right there on the premises. They'll have many of your beater components right there, at the Bike Kitchen.
I don't know anything about your budget, but if it were me. I'd wait for an old 80's styled chromoly steel mountain bike. I'd have it powdercoat painted matte black and throw some wide tires on it. I'd also equip it with fenders, rack, and panniers. That would be my main go-to steed for everyday riding.
I would then purchase my illustrious road bike. My recreational road racing bike....
Good Luck, my friend!
PS.
You'll find that your mass transit options can get very old, very fast. It's expensive, heavily laden with crowds, and comotion. It can become quite hectic! In the interest of your own personal health and sanity, use the mass transit option sparingly. Always try to rely upon cycling as much as possible.