Need help! Zombie & Cop spawners without being cliche!

Hi guys, I am working on my gamemode map and only have 2.5 weeks until my first beta release. I need some advice on how to do a zombie & cop spawner without being cliche. This is not the actual entity, but where the baddies come from.
What should I do? It Is sort of a downtown grimey map, so, yeah.
Thanks guys!

This is a really vague question… can you elaborate a bit?

Maybe take a look at the Ravenholm source map and see where Valve placed the spawners. If I remember, a lot of them were placed in dark alleyways.

you could have cops rappel from roofs