I've created a shortlist of 3 battles that we could turn into a Very Big Battle for 2011, and I'll briefly post on each over the next week or so; then we can take a collective decision about which to go for. I'd anticipate that all 3 projects would be a similar size, with c. 2000 miniatures on a 20'+ wide table based on the Zama terrain.
The first battle I'd like to look at is Chaeronea, 86BC; a big engagement fought on a flat plain in a Greek valley between Sulla's Romans and Mithridates' General Archaelaus, which is described on Wikipedia. It is, also, a battle we've previously fought (links to the 3rd part of an article about our game).
Here are some links to photos of the plain near Chaeronea, including one from the hills. The Zama boards would lend themselves very well to this, and a couple of large hills could be sculpted to represent the edges of the valley. There is also a river, a fortified hilltop and IIRC there may be a temple; all potetiallly striking terrain, and where there was also some fighting. It might be possible to fit a camp in, too.
Other plusses are that the troops types involved are fairly varied, and include pikes (including a phalanx formed of former slaves), scythed chariots, thureophoroi, Skythian or Hellenistic heavy cavalry and tons of Romans. No elephants, iunfortunately. One further plus is that I already have quite a lot of painted suitable for this game, although in a sense, this is also a minus in that there would be less to paint, and painting everything for Zama was half the fun. Still, we could up the numbers and make the game absolutely huge.