I've had great success with Green Ronin's Mythic Vistas books. I don't play any of them precisely by the book; I mine them for details instead. Most recently, I picked up Hamunaptra and had a blast running a series of adventures using a lot of the material from it. We sprinkled a few bits from Testament in there as well. With those two books, a pile of history texts from the library, and a viewing of several choice movies, I had the whole game nailed for weeks.
I don't like how exhaustively some of the official settings are documented. I started running Eberron last year when the setting book came out and have found that as the later books came out, they were contradicting a lot of what I had done in the months before their release. Rather than try to resolve the differences, I just elected not to buy any of the later Eberron books. I stopped with the Sharn book. I imagine that when this campaign is finished, I'll have to decide whether to bite the bullet and invest in the rest of the source books. Early signs indicate not.
I look forward to the Wilderlands Boxed Set. If its anything like the original, it will fit my needs very well. I don't want to read history, I want nuts and bolts encounters and such. I can make up my own history and would rather not have to worry about diverging from the published setting.
It really got annoying when I returned to Greyhawk shortly after the Living Greyhawk Gazetter came out. I'd played Greyhawk for ages back in the day and suddenly here is this treatise on a Greyhawk that wasn't my own. I found that my newer players would expect the Greyhawk from the Gazetter and would be disappointed when -my- Greyhawk was different - even after I warned them of this very fact.