Don't fiddle around with a flat bar bike. For the amount of time that you'll end up wanting to spend on a ride, being stuck with one hand position -- and a high, non-aero one at that -- will start to get annoying and, ironically, less comfortable than the hybrid marketers will have you believe.

On the other hand, a hybrid will do okay while you decide where you like to ride the most. Once you figure that out, get that second bike specifically for that purpose. Then you'll still have the hybrid as a backup bike, for friends to borrow, for more laid-back rides, etc.

(my post isn't much help, is it? )