Personally, i think the server should be more PvP oriented. I don't believe that you will get more people on the server, by making it more PvE, and building.. The minigames and all that are really cool, but it could be nice to add a plugin like Towny or something, to actually make it cost something to have a town. That way you dont "just" have to mine gold or diamond, to get one..
Also i think, making the map smaller, by putting a world limit on, would be sweet. Like if the world was limited to only -1000 to 1000 blocks in both directions. That way you bumb much more into each other, and are more forced to PvP'ing.