Region Size
Hah same. I agree with everything nickeox has said, but I have some points I'd like to add:
1: Maximum region size should not apply to anything built by hand that exceeds whatever the size is set to. However, players can not exceed region size by making small builds along the edge of a region and leaving the middle empty.
2: Maximum region size will be determined by side length. No side shall exceed n blocks. Exceptions for long and narrow regions, such as roads and minecart rails.
3: Cadmins may not approve their own regions for exceeding region size. For example, jchance would have to ask LetsBFehr, Marting, or me if he wanted a large region.
I think to help keep things simple, the maximum region size should be large enough that you can't see a corner from the opposite corner. If you can, then no need to worry. If not, then you'd have to check.