well...to match the plot, i'd say that you should make a small island-type thing at the top. blue team starts up there & red team starts somewhere in the facility. this means the the elevator would need to be working. i think that would be cooler but who knows...
this way you would have to work as a team though, think about it...you've got 8 people comming down an elevator, you reach the bottom & boom. red team through a nade right when you came down.
not too smart if you ask me...but, lets say you send 5 down then 3 after them, people from your first team die then you come down & back them up...(of course that almost makes it too easy for the red). maybe you should have two elevtors...1 on each side of a wall. while 1 goes down the other goes up. & this idea would also be fun & interesting in capture the flag(two elevators...).
so, what do you think?