I'm working on building a symmetrical two-flag CTF map in the Colosseum of Forge World. I didn't start sketching on paper or my computer, but as I've been building and finagling I've been trying to focus on making sure that the most effective routes have appropriate risk attached to them. I'm not sure how I'm doing though. I want to build a map that allows for some spectacular and impressive plays, but I want them to be tricky to pull off. Right now, my map allows an offensive player to sweep in one side of the opposition's base to grab the flag. They can escape not only via the three ground exits, but via the one-way shield right above them, bouncing onto the base's roof. A few quick hops get them to a Man Cannon that carries them to the top of the wall that divides the arena in half. (And at that part they seem largely home free.) I think anybody who builds a map wants to enable awesome plays like that - the kind people make clips of and post in their fileshare. But I don't want to make those awesome routes too easy - otherwise there's little point to having any other routes? Why carry the flag out through the ground exits when the roof exit is so accessible? Why run back to base when you can jump on that cannon? I've probably run on too long - but how do you balance those great routes in your map? How do you make them more difficult to hit? I want to build a good map here, but in this one I'm concerned that one specific path renders the others almost useless.
Risk vs. Reward is easily the term used in Forging that is blown out of proportion the most. Anyways, I'd really reccommend using a program like Google Sketchup to predesign a map before building. While using sketchup it's much easier to change things about the map than it is in forge. I'd also reccommend you read through this handy little guide on map design, if you haven't already. This will help you with the general bits and pieces that are designing a map. Now, on to my reccommendations. Seeing as I can't actually see the map, I can't help you much, but I'd probably reccommend making longer lines of sight to the top of the bases and have little to no cover on them as well.
Give the enemies sniping weapons or other counters. Place them outside the base so enemies don't steal them (since the enemies that these weapons are meant to counter will actually be in the base shortly before the weapons are needed). (Like Hemorrhage's Concussion Rifles on the ridges.) A significant risk of death, should a player attempt your "epic route", is also a good counter. ("Oh, dude, sick! If you'd been even an inch off when you went through that cannon, it woulda splattered your ass! Epic, man!")