My primary objective for the 1284P is to get the additional RAM (and code space). Also needed to maintain the traditional Arduino dimensions and header locations, including ICSP. There is more then enough IO on an ATmega328 for my purposes.
When I thought out the board I made some compromises. The 32u4 board I did has a lot of empty space. Could have easily placed a regulator and just choose to not populate if not needed. Once my prototype is tested I just might re-spin with that.
For this board, I ended up with plenty of free space as well. I decided to add a regulator, not thinking of the available IO. In retrospect it may have been more sensitive to dump the regulator in favor of an additional header for the additional available IO. Or could have tried squeezing a bit more. But there is also a time constraint, really needed to get this done, more so then the 32u4 which was just a learning exercise.
So all considered, it is built with my particular specifications in mind. Once I get the boards in my hands might re-spin them anyways. Need to iron out whatever bugs I discover. Also depends if there is any larger interest in the two designs I did. For the 32u4 it would most certainly make sense to add a regulator, there is just so much empty space on the board. For the 1284p I'd be more inclined to drop the regulator and add a header for I/O. We shall see....
Right now I am just tickled by how easy it is to get prototype boards made. I've been pretty absent from this stuff since 2005 or so. Last board I made was a PIC based ethernet board. DIP chips and mix of 0805 and through hole parts. A single sided PCB made at home using toner transfer. Was looking at commercial boards, but cost then was much more for a single prototype run then it is today. If I remember correctly, back then the best deal I found was in excess of $50 for 2 boards. This may have been a bare board without silk screen too. Maybe I didn't look hard enough back then, but I don't think BatchPCB, Seeed Studio or DorkbotPDX were around those days. Anyways, I have been pretty anxious to get a couple of interesting boards whipped up and getting them made. Now I need to wait for the mail man. 
*man... How many times do I have to edit my post to fix the iPad typos? The auto correct of the iPad is as much of a curse as it is a blessing...