Rethought, somewhat;
Races of the Horde:
Goblins, hobgoblins, bugbears, orcs and trolls. This book would be as crunch-lite as is possible for this kind of book. It would aos include the options for playing these evil races as evil PCs, and as honestly good heroes.
Length: 180 pages or so.
Why? Because many people are asking for it.
Sinister Shadows:
All about the secret (and not so secret) presence, influence, goals and operations of demons and devils in the campaign world. It is not about what they do in the Abyss or in Hell.
Length: 120 pages or so.
Why? Because it is evil and cool.
Eberron – the Unexplored:
Detailing and exploring several regions of the Eberron setting that have to date received only nominal attention, most likely the planes around the setting.
Length: 180 pages or so.
Why? Because everyone is asking for it.
Grayhawk:
This would update the setting and make it clear – it would also be carefully worked out so it supported what the RPGA is doing and does not create conflict.
Length: 220 pages (it deserves that much space).
Why? Because everyone is asking for it, and really when was the default setting really visited?
Forgotten Realms – The Heartlands:
This book would cover the Heart Lands, both central and western (i.e. Cormyr, Sembia, the Dalelands, Elturel, Baldur’s Gate, etc.) More attention would be given to Cormyr, Sembia and Dalelands.
Length: 220 pages (it deserves that much space).
Why? Because many people are asking for it.
Sigil:
This would make the city at the heart of the multi-verse updated and made as compatible as possible with DnD 3.5 in general and all the published settings. It would not re-launch Planescape.
Length: 180 pages
Why? Because everyone is asking for it.
Forgotten Realms - Beyond Faerun:
Al-Qadim, Mazteca and Kara-Tur, would be covered, updated and made as compatible as possible with at least one of them deserves a revisit and people keep asking for it.
Length: 220 pages or so. (about 70 pages for each setting).
Why? Because everyone is asking for it.
Expedition to Spelljammer:
An adventure that takes the PCs from their world to intra-planetary travel, dealing with all the best of the Spelljammer setting. It would draw much from the Polyhedron article from a few years back (including the fact there is only one crystal sphere that matters – the one home to the PCs world). It would be designed to fit into any campaign setting and would not re-launch the setting.
Length: 180 pages or so.
Why? Because no one is asking for it.