I suggest making all ranked games to be set up automatically with a default map (the memorice seems to be the map that's played 90% of the time).
How this would work: Click the play button and you enter the queue, which tries to match you with players of similar rating (the longer you're in the queue for the larger the rating difference will be allowed so as to keep from waiting too long)
You could allow all the free customizations still but just make those games unrated. This would help with the problem of 'teamers' and having high rated players making a new 1400 ranked player to cheat with.
A game called League of Legends (www.leagueoflegends.com) uses this type of system currently and it works well, though LoL is a team based game and I feel DominateGame would benefit more from it.