kayak.com and I find Orbitz is usually the best for airfare.
Southwest is good to check also. I just booked 5 tickets for $855 for this Aug. and it's a non-stop flight. We are actually leaving a day earlier b/c we were going to break even w/ the extra night and the cheaper fare.
I read where someone booked their tickets for next March already and payed like twice as much. Just my opinion, I would never book that far out unless I had an awsome deal. Watch, watch, watch. I cannot stress that enough. And don't panick if they go up. They will come back down. I watched and waited and missed the boat to see the tickets sky rocket and they did come back down every time. Now, I'm not saying they've been the deals of the past, but they have been reasonable. Good Luck!