Russ, I really doubt WotC's going to sue us if we offer suggestions as fellow gamers who just happen to know the adventures intimately. I'm not a lawyer, but we're not using their IP to sell the product, and we're not misappropriating their characters or settings.
In Forgotten Realms, since some of you have asked, I would run the campaign in the Unapproachable East, with Ragesia becoming Thay, and Shahalesti becoming Aglarond. You basically would rotate the map 180 degrees, so the party starts in the mountains between the two nations, and flees northward to . . . I think it's Thesk, which would be a good stand-in for Dassen. If you want it easy, set the campaign in the not-too-distant future and say the Simbul and Szass Tam killed each other (so the power vacuum involves the fall of the high zulkir, not emperor coaltongue). And Leska could be the Zulkir of Abjuration. Easy.
I'll look into Greyhawk possibilities, but I don't know the rest too well. However, it just takes a little imagination, and I'd be very interested to see what people's ideas are.