I was just poking around on AA yesterday and found international premium class saver availability quite open compared to what I was expecting. Sure, you're not getting a cheap business class ticket to FCO in June/July/August, but the people that got those (if there were any) probably booked them 330 days out.

Flexibility (in timing and routing) and creativity (in routing and airline partners) is going to be the best rule of thumb. When a website doesn't find availability, call and talk to the agents. Paying the agent fee is better than paying double miles online.