So it seems like people have been coming up with a lot of demigods, why not maps? Here's two I've thought up:

Forest:  A big, lush forest with three, really long paths to the enemy base.  However, there's a bridge not far to the north of your citadel.  If you hold the flags on both sides, it raises, saving you a ton of time.  If anyone captures just one of the flags the bridge lowers again, killing all units that were on it.

Sea:  Your team starts out on an island.  There's enough space north of the island to contain space for fighting and ships.  You can control these ships and transport both you and your minions to one of multiple islands in the area that contain flags.  (Some flags will gain you more ships, give ships special upgrades, etc.) There's different flags on different islands, and should you meet an enemy ship, your army may either engage them using ranged attacks, or run.  (Note, these are really large ships, you be able to control all units that are on the deck, as well as demigods)  A ship has the same movespeed as a demigod, and ships will count as citadel upgrades for minion attack and armor.  Also, there will be a flag on both islands near the citadel that controls ship production.  If a ship should fall, it will undergo the same respawn time as a demigod.  Each team will start with two ships, but once again certain flags will increase that number.

Blizzard:

A large arena with multiple paths, (can't really think of a unique design) with random blizzards that completly cover your field of vision.

Also, it'd be interesting to see some new flags.  Bridges would be an interesting choice, but at the moment nothing else comes to mind.  Anyone else think of some new maps?