A while ago (a few months) I posted a map illustrating an idea I had; multiple flag CTF. Many people made good suggestions for how to improve upon the concept. This map is the result.
Each team has a main base with five exits (four teles and a drop out), ammo, and armor. The four flags are at the four ends of the main cross of the map. Each team base is between its two flags. This map is quite large, intended for ten or more players per team.
For people who may not have read my previous node, you can score an enemy flag at either of your flags, you don’t need to have both of your flags safe to score, you can only carry one flag at a time. You don't need to change anything about your game files for this map to work properly.(There’s even a variable in the ctf game code that specifies how many flags can be carried at once.)

I’m not going to say that this is the best map ever made, though if you think that it is, that’s good I guess. I don’t personally think that I used the gor texture set to its best extent. This map isn’t as nice looking as Hallo, Infamy, or Abbey. However, this is a much better map for double-flag CTF than the previous map I made using this idea.

Areas that are possibly unbalanced/need work:
-The tele in the main map from near one flag to near the other. Does anyone think that this makes the rocky flag too much easier to get to than the other?
-Weapon placement and amount. I still could use some work on balance. Should there be more pickups? The other complaint about my pickup placement in the past has been that you have to go out of the way for pickups. Some of the pickups in this map are right in the middle of the path. Others are not still. Please keep in mind that I intend for players to stock up somewhat in their bases also. However, there is also the issue of weapons for Hold mode, because this map also has capture bases.
-Narrow low passageways. This was the biggest complaint about my past maps, and hopefully no one has problems with that in this map. I have tried to make the doorways wide and tall, so hopefully there isn’t much on those lines to complain about on this map.

I added capture bases because there was no real reason not to with such a large map.

http://www.quadropolis.us/node/3688 - Previous node in which I posted the first map made around this idea, in case anyone cares to look at/read it.
Looking back at that node reminded me that RaZgRiZ said that he’d had the same idea before, and that he also suggested a cross format. Thank you for sparking the idea for this map’s design! (actually, others said that the idea had been bouncing around in a small group for a while, well thank you everyone who may have influenced this map)

Thank you in advance for checking out this map! I hope for some interesting feedback about this map or this application of the dual-CTF idea.

[Edit] Wow, i edited this twice within minutes of posting! I originally forgot to specify map size and license, and this second time fixes a couple grammatical errors, though I probably still missed some.