Bustr is right about the score part. A lot of people are concerned with scoring and base taking strategies. A lot of people do like to gauge their statistics and kills and so on. The custom maps aren't going to work because of the way the tabs are set up. Most people don't even see the tabs or will even click on them before they click on the Melee arena. They all need to be on the same page. A smaller arena that make sense, like Smog 8, where people actually undertsand the direction of the map, will keep people who play inside of it busy, while allowing for structured fights to take place, create furballs, and action that is easy to find. It would be really helpful to new players who don't understand the large map big game flying.
Or you can add a simple FFA with 5 airspawns at 3K, that would create action fast combat for days. It would truely allow people to learn the game better and have a lot of fun for people who don't have a lof time to play that sitting.