The best deck to play in arena imo is Fluctuator. It wins on turn one or two every game and its fun to play. No one who is smart will play with counters so your home free. I reck ass every time i play it in arena ill post a list as soon as i can.
Luis

if u go to http://webapp.wizards.com/dcitournament/ u can locate sanction tourneys near your area.
hope that helps and good luck
Luis