I'm not sure if the original poster is even reading this thread anymore . . . but just for fun, here's my experience.
I looked for several months at bikes--road bikes, hybrid bikes, "urban" bikes, single speeds, multi-speeds, cyclocross, etc.
After riding a zillion of them I decided on a Marin Muirwoods. It's the lower end of what they call their "city" bikes. Basically it's just a 26", fully-rigid MTB with full braze-ons for fenders, racks and water bottles and comes with slick tires.
For what it's worth, I think it kicks serious ass in the commuting department. I ride it about ten miles a day and it's holding up well, so far. I find the upright position ideal for keeping a look out in traffic (plus it's more comfy for me . . . a holdover from my teenage BMX days, no doubt), the gearing and shifting to be smooth and the steel frame and MTB tires eat up potholes and even handle curbs pretty darn well.
Am I saying you should buy this bike? Not really, unless you ride it and like it like I did.
But you need to ride a LOT of bikes. All different kinds, even ones you don't think you want. You never know what's going to feel good for you to ride on and it'd be a crappy mistake to spend that much hard earned cash to get something you won't like riding.
But again my .02 cents?
Fully rigid MTB's (which no one seems to make anymore, barring the 29ers and SS) are awesome for city riding.

P.S. I agree with whoever said to buy an old Specialized Hardrock and put slicks on it. Great for a city bike on the cheap!