Dungeoneering is probably where you should start. You're right, double nats aren't that good any more. At the moment, Frost Dragons are pretty much the best way to make cash, 2M an hour with a War Tortoise and over 3-4M with a Pack Yak. So I'd go grind your way to 85 Dungeoneering and get a Chaotic weapon, which are pretty much the best weapons around.