i have an idea that there should be a  pvp arena with an airship but here is a new idea for it :
1: you can build TNT cannons
2: You need build bridges to base at a certain time
3: the arena will give you items ( Stone, TNT , swords,bows,ect)
4:There is a certain goal for the team to win
5: there can be 2 versions like hardcore mode and team deathmatch
6:In the area tnt is allowed
7:There will be teams like (so and so) and team (so and so) (there should be a thing when you get picked on a team the team color wool will be put on your head

Hope you like the idea!

I agree with Krazzy, but getting creative with the pvp arenas would be fun. If we could play in different arenas like a ship or something. Sort of like how maps are in PS3/XBL games.