My idea

[o_slinky]

I think it would be cool two have two bases opposite each other with garages. In the garages there would be two ways to get to the enemy's base. The road, or there would be a secret passage way that you could drive off of like a ramp and land in front of the enemy's base. I don't know if this next thing would work but maybe you could blow up the bridge if you were a demoman and you could rebuild the bridge by detpacking a pile of bricks lying next to the spot on the bridge you would blow up. To make the map really cool you could have a basement you could watch over like mulch_dm and if you can cars together and make them fly up really high then you could have car battles and launching. I have no idea if this will work but I think it would be an awesome map.

http://tinypic.com/1oakv5 That's the diagram for it