Also depends somewhat on where you want to go. I don't see many business or F class sales for flights to Asia ex USA. Of course there are often cheap fares for going the other direction but then you still need to position.

And it depends on how much you're spending on the Discover card. As noted, bonus spend categories, UR or airlines site "mall" bonuses, sign up bonuses, etc can help you accrue a ton of miles for not a lot of spend.

Personally I've never had a problem finding the award seats that I want. It takes some planning and flexibility sometimes though.