Playing arenas is a new challenge. It's similar to doing a pull in an instance except it's different because you don't know what mobs are coming in that pull, and they're not so... repetitive.
As with most instances the key to "winning" is proper communication and people doing their jobs well.
Today's setup is designed to give you a big open screen space to see around you while still giving you all the information you need to keep on top of every mob.
We start by using ElkBuffBars to move our buff / debuffs to the top corners of our screen. Pitbull party, player, focus, and target frames line the left of your screen. With debuff highlighting built in to Pitbull you can quickly see when a friendly player is in need of help. Along the top is Control Arena, a newer arena target frame AddOn that let's you see all of your opponents and what they're casting. It also shows when they're crowd controlled so you know who to avoid easily.
RicoMiniMap, EePanels2 and Bongos 2 round out the layout.
When I'm doing arenas one of the most frustrating things is actually the part before the arena begins. Buffing. Enter ZOMG buffs.
ZOMG buffs puts a single "action bar" button that's movable on your screen. Simply assign buffs to every class and at the start of each arena start smacking that button until it's all clear. Done.
If you hover over the button it shows a display of everyone in your group / raid and what buffs they currently have.
The final pieces for our setup are AZCast only showing my target's cast bar right in the middle of the screen (which you could add focus right below it to watch a healer or other) and ControlFreak which simply watches your focus target for crowd control. I recommend using a macro any time you have a crowd control that's used a lot in arenas.
Something like :
/clearfocus [mod:alt] [target=focus,dead] [target=focus,noexists]
/cast [target=focus] Polymorph
/p CCing %f !
This macro allows you to set a target (healer, etc.) and for the rest of the match cast your crowd control on your focus without changing your current target. You can of course change Polymorph to whatever cc you'd like and can change your focus by simple holding alt while you click this. If you set ChatMod's highlighting function to watch for "CCing" it'll give you a nice warning before the cc lands so you don't break it right away. =)
ControlFreak watches your focus frame and gives you an audible warning whenever your cc breaks and can even be clicked to recast as well.
A last minute idea I had after putting this together was to add in MobHealth to get an educated guess to your opponents total health on their frames.