Cancun, Mexico (39%)
Punta Cana, Dominican Republic (36%)
Paris, France (28%)
San Jose del Cabo, Mexico (27%)
Rome, Italy (25%)
Montego Bay, Jamaica (25%)
Barcelona, Spain (23%)
Manila, Philippines (20%)
If one of these destinations strikes your fancy, then get to shopping. Or you can try Hopper, which gets excited to share data for just this possibility. Enter the dates you want to fly in the app, select your home airport, and enter the city you're traveling to. Hopper will send you alerts as the flights are dropping.
Much like with any price predictions, you won't KNOW when they've bottomed out, and you might still end up sitting next to a guy who'll chew your ear off about how he paid $27 less than you did. But take Neil Patrick Harris' advice, pack some noise-canceling headphones, and enjoy the fact that you bought low while most airfares got more expensive.