After looking around at all the shields people are making based on the Decimilia board, I decided it would be best to start over using that as a template. The goal here is to make a board that's compatible with what's out there so it's actually useful instead of being a novelty item. I spent all day trying new layouts and wrestling with traces, and I'm pretty comfortable with the result:
All the pins line up exactly with the Decimila board, and there should be enough room to the right so the ZIF socket doesn't get in the way. I'm going to be using Gold Phoenix for manufacturing this time around to get a lot more bang for the buck. There'll be somewhere around 15 boards this run to send out to those willing to test.