I have a couple of good H3 map designs like a forest map with a waterfall you can jump off of down into a pool of water that has a small base around it.
A map based off of the first mission. Maybe the damn part or the part of the mission where the Pelican gets shot down by the 2 banshees. That would make excellent gameplay. A map inside High Charity(the flood infested one) from Cortana's mission Ooooh, the last mission beginning. The little arena before you get to the stairs. Both teams start on a side of the building.
I've got a map design called Sand Lot in which there is a scarab on both teams.the teams also have Elephants that have slightly increased speed. this would be a 16 on 16 match. The teams would have hornets in which to take down the scarabs (like in campaign).