I've literally played Skyline, Statue, Pier 17 and another small square map dozens of times but maps that appear later in the rotation I've only played once or twice. I'm up to level 20 and still don't have the achievement for playing a round on every map.
I've also noticed that the same maps are always pitted against one another for the vote.
The map rotation needs to be completely randomized including which maps are paired against each other.