Yay, I'm back.
Anyway, here's the ideas.
Arena_deserted.
Basically the Meet the Sniper map that was never in the game.
koth_rockfort
The Meet the Medic map that was never in the game.
cp_waterfall
Alright, now to my ideas.
Both teams start on top of two waterfalls, red on one, blu on the other.
There is 3 control points on the map, 1 at each base, and one on the middle, which is a huge bridge.
Falling off a waterfall or a bridge will cause in environmental death.
koth_spiral
A bit of this is a rip off of Banjo Kazooie, but still.
The control point is located in the middle of the map on (you guessed it) a spiral mountain.
Teams start from opposite sides, and there is no way of environmental death, other than drowning on the ring of water around the mountain.
That's all I can think of, really. Feel free to share your own ideas!