I think it would be hard to go wrong with just about anything in that price range. Only, I wouldn't buy online. I think if you are going to spend that much you want to go and do some test riding and see what you really like. Find a shop or two that you like and vist often. Shouldn't take too long for a couple bikes to start to speak to you. Ride them. It will become clear which one is right.
EDIT: I second the suggestion to stick in the $2,000-3,000 range and save some for wheels. Stock wheels are not all that bad in this range but I think it's more fun to get better wheels than spend everything on a more expensive bike for the component upgrade. You are already in the 105, Rival, Ultegra range so can't really go wrong. Bike manufacturers seem to cut corners on things like bars, stem, saddle, wheels and I'd rather upgrade these contact points.
Last edited by bikerjp; 01-26-13 at 06:57 PM.