I was just digging out a celler recently, and an odd thought occurred to me: why not make 2-story buildings without any extra drawing effort on Jorb's part? You can simply re-use the celler code.
The idea is to make a loft, or attic as an attachment to the current buildings. You build it in a somewhat similar fashion to how you build a celler. Place a ladder or stairs somewhere in the building. These should require a large number of boards, to simulate making a ceiling that can be walked on. Then presto, you have yourself a small attic which can be used for storage. Obviously, this should probably be smaller than the actual building size, meaning log cabins would gain next to nothing, whereas mansions would stand to gain a bit by putting this in.