If you don't have a specific airline in mind for the actual flying, it'll be a lot of work, since ExpertFlyer searches one airline at a time (instead of an alliance at a time), and it doesn't offer award searches for every single airline.

You might instead want to use Award Nexus (www.awardnexus.com, click "more signup options" under the green Purchase button to sign up for free using your FlyerTalk login info). It lets you search an alliance at a time (using one or two different airlines in each alliance). AA's website isn't able to search all their partners, I'm not sure about UA or DL. One nice thing about Award Nexus it that it uses the same user interface no matter which airline's search you're using behind the scenes. Award Nexus is free (for FlyerTalk members) up to a point, but if you do a lot of searches you might have to pay a bit (but still less probably than for an Expert Flyer subscription).