I have a idea for a two sided assault map. Its in a U shape and the teams spawn on each ends of the U. Each team starts out with the bomb, and they have to bring it to the other end to score. (Don't worry about spawn issues because you spawn in a safe room the other team can't get into.) When one team scores the round is over. So how would this sound gameplay wise? (please don't steal this idea)
If you were going for multiple scores to win, and you didn't want everyone in the room blowing up because of someone scoring, I could see the usefulness of a flag... But ya; assault...
So its bombquest? Conquest with bombs, could be cool spinoff Eglourious 3 or whatever the name is has made a map that has an idea similar to this, could help you out with the map Here ya go:http://www.forgehub.com/forum/competitive-maps/100483-time-capsule.html
Your map will hopefully not be able to be described as just a U. I would recommend looking at what others have done with U-shaped maps and find out what "worked" for them. Then utilize those concepts in your own map. Beyond that there is not much to say besides this is not an original idea so I don't think you have to worry about people "stealing" it.