I have just a very small and simple suggestion, which I would imagine would be easy to apply.
I thought it would be a good idea to have the maps that you can vote for (that haven't been played the last 10 rounds) to be highlighted some way (be brighter, white, etc, or to just stand out from the maps that can't be chosen). This way, obviously, it's easier to see what maps you can vote for, and you won't spend for ever looking for the map you want to play just out that it's not playable. (will be easier to identify)
