Matt that's a very nice mill plan, lots of switching!
Joe what buildings do you have so far? Mills get a wide variety of frieghtcars so plan with that in mind. A 2X10 area is plenty of space, especially if you split the buildings and place them against the backdrop.
My layout had to come down to reinsulate the walls, I am just drawing up my next mill now mainly based on the Walthers papermill series.
I'll keep you posted as I go, maybe I'll get around to starting a papermill group as we discussed earlier...
My wife always says I don't pay attention, or something like that.