[rdonj]

Alexander - Might be possible but it seems too messy for what I'm envisioning.
Glory of the Gods - Probably a better choice than alexander. You'd have to array the noobs around the top and left side of the map to give them enough space, with the vets in the bottom right area. Problem is I think you'd have trouble leaving routes for all the noobs to attack the vets without stepping on each other's toes.
Symmetry - I agree with trumanator here, at least one of the noobs is going to be left largely on their own to deal with at least one of the vets early on. I wouldn't give that player much chance.

This is why I think Orania is a good choice, you can place people however you want and there are no natural funnels that will hamper logistics. On the other hand, maybe orania is a little too open, and a random map with a few mountaints would be better.

It wouldn't be very hard to make up a preset start version of whatever map is chosen, so really that part isn't a big deal.