General mod Questions/suggestions/Idea's/thoughts

Im making this for the simple reason that should people have anything to say about the mods, they can talk about it here.

My question is: Should the zombie map have an underground?
The above ground will be offices and roofs, somtimes on the street. The metro will be darker, have fire, and be more dangerious... but be more direct. I am thinking possibly 3 exits...
(M=Metro entrance/exit)

Start-----(M)----Mid(M)----(M)--------End
Somthing to make the map have a lil more play... say if you get half way in the underground and realise its not good.. you can switch or vise versa.

**The end will be a X:XX min train wait... it'll be set and adjusted to how long the map is.

Win = Zombie Apoc + Underground (be it subway, or sewer)

Please, do include :D