I've had luck with my American and USAirways, because Star Alliance has SO many partners, American too. Maybe depends on where you live, and what hubs operate there, as well as where you like to go. I really like American and United, because both have one way fares available, and you can mix two for one award at same points. Did that last time, using BA miles to Europe, and home from South America with United.

Delta points for me have been good for getting to Africa, or at least paid upgrades to biz class, in my experience (only 25K each way, and you still earn mega points for miles because it's so far). If you ask me, that's about it, but they are notorious among the flyertalk people for being difficult in getting award seats. I have stopped using my Delta Amex for just that reason. Once I paid double points, full RT both ways, because I was flying to and from different "regions" (South America and Africa on a crossing cruise) Marc Levin may have different thoughts.

Seems lately I never have luck anymore on my own. You call your own airline, and often they cannot see what is available within the consortium they are in. Then, I just call one of the points people, who are great. Guys with other jobs who just make extra money, charging a few bucks compared to the cost of international air and can find you what you want for $250 per couple, no matter where in the world.