Further developments:
I spent most of the weekend trying out bikes from shops and buddies. I learned a few things.
Drop bars really don't suit me. I've an old back injury from years ago (a very slapstick accident, but a story for another time) and after a mile or two, I'm as stiff as Hefner in his 20's.
Racing Saddles are great once they're "warmed up" in a little (and your arse gets used to them), and ultimately more comforting than those gel-filled thrones sold for comfort.
29" wheels are definitely better for top speed and distance, but something of a bitch for acceleration when compared to 26" or 700C's
Riding a bike with a 15 year-old Shimano SIS drivetrain has pretty much deadened my senses to the subtle distinctions of newer running gear. Pretty much, everything is better, quieter and smoother, and it'd be some time before I would even notice the difference between entry level and competition grade.
As I suspected, unless you're actively seeking out bumps, suspension is just weight you don't need. Rear suspension in particular is a little silly for road riding, as I was born with knees.
In conclusion, though, in my price range, it's nip-and-tuck between bikes. I'm pretty well aware I'm not going to be able to get everything and a cherry on top, so I'm going to have to pick the one that gives me the strengths I want, and the flaws I can live with, or iron out with money later. I'm vacillating between the Cannondale Bad Boy, a Giant Rapid 4 and a Specialized Sirrus Elite. It's probably going to come down to price and gut at the end of the day. The Cannondale is marginally ahead, though, as the other two bikes are in a shop where manners and customer service apparently don't exist, and I'd be loath to give them the proverbial steam off my piss, let alone half a grand.