I'm kind of in the same boat as you. I'm coming back from a knee injury and looking at what I want my new commuter to be. I want something capable of keeping up on the weekend rides. Yet something that can take a rack, panniers, and at least 28 tires for commuting.
I'm pretty much settled on the Giant Defy line up. I'd stick with Aluminum, although you can get a carbon model in that price range. (I don't think the carbon models are rack/fender ready) The Aluminum frame has rack mounts, and I know they have Defy specific fenders from Giant, http://www2.giant-bicycles.com/en-pa...ies/338/28915/
-Giant's Aluxx SL is probably some of the best aluminum in the business. The Defy rides like a dream, and is more than light enough.
-Shimano 105, nuff said
-rack + Fenders