Associate
The CSS server should maybe rotate Office, Nuke, Italy, and Dust2 I'd say. Keep it to the more popular maps then maybe add more later. Make it force a pistol round and standard money settings maybe?
start with a rotation of 4 standard maps n 2 custom maps
also have a list of custom maps you have on the server n every couple weeks switch the 2 custom maps for another 2 to keep things diferent
thats how cpc server does it, keeps things fresh