Best way is literally to force feed the maps to people. Put them on your server with a redirect on, then proceed to ask literally everyone who joins your server to play marketcenter, urban/dusty, or whatever else. With backlot_fix it's even easier, if they ask for backlot, just put it on the fixed version, causes no harm whatsoever.
Quite frankly, I'm not sure why cluster has become popular while marketcenter, urban/dusty, portside and other maps have essentially flunked. In my opinion, marketcenter and dusty are hands down two of the best maps in the game, while cluster is barely playable.
Also, PUT THE MAPS IN THE PUG SYSTEM ON THIS SITE. That alone will increase their popularity exponentially.
Edited once, 18/8/11 - 2:00am.
Posted on Thursday, 18th August 2011