Sounds like a nice mix. I've got the Tubus Vega rack on the Bianchi, very light and still practical. That and a trunk bag should handle your requirements based on what you've said. As for the cassette I'd throw a mtb one on it, so that you get a bit more versatility for what ever you want it to do. throw the corncob cassette wheelset on it for club rides and toss the mtb cassette wheelset on for when you need that extended low range. Hopefully the two rear wheels will be built close enough to eachother that you won't have to do too much adjusting of the RD. If you go with the MTB cluster, you will 'probably' need to get a second chain for that one due to the length differences.
I've got SK fenders on the C-dale and Bianchi, and found them easy to install and not too hideous looking. The Commuter ones are a bit short on the rear, the fulls are a bit longer. You can always rig up a flap for them as needed.
One thing, with a cyclo-puter different sized tires are going to effect the calibration, and you may have to remember to adjust the 'puter, or get one that is designed for multiple bikes and has different profiles you can switch between.
Like I said, sounds good to me, seems close to what I'd build, but that recommendation and a 5 dollar bill will get you an expensive coffee drink at some trendy latte shop.
Steve W.
Who likes his women like his coffee, warmed over and bitter