What setting book or guide is the best for developing other settings? What would you recommend, with or without caveats, as the "Go To Source" for what a setting guide should look like?
As I say above, Ptolus is my go-to.
I stick with that answer, but I'm going to add some extra thoughts here.
I'm working on my own campaign setting. Well… I've been working on this version of the world since pre-4th Edition. And now I'm poking away at a revision that might be OGL friendly that I can throw on DriveThruRPG. But I'm mostly doing the formatting so I can get myself a Print on Demand copy of my world as a lovely vanity project.
For that reason, I've been considering format and presentation.
A PDF is nice and searchable, but so is a wiki. There are some campaign sites like Obsidian Portal or Epic Words that can hook you up with simple wiki software.
At the table, a PDF on a tablet is super fast. And a page remains found even after you turn off the device. Plus a quick keyword search is hand.
But there's something useful about a print copy that you can flip through, pass across a table, or write notes in the margin.
Layout? What has the best structure for reading and referencing? Which setting publication is so easy to use you can find everything you need quickly?
There's really only two structures I've seen: alphabetical, and then region and then alphabetical. The former lists every nation arranged by its name. The latter divides the world into various regions and then lists the nations.
The former is useful when looking up random lands, because each nation is easily located. It's a little more awkward when first reading the book, as you'll bounce around the geography.
The latter is more useful when running, as related nations are just closer together. Athens and Sparta would be close together rather than opposite ends of the book. And it can be easier for new readers as nations that impact each other are close by. But it's trickier when looking for a single nation when you might be uncertain where it falls in the order. (Is the Swiss region in "The West" with Gaul or "Germanic Forests"?)
A third way might be a deliberate East-to-West presentation of lands (or North-to-South).
Really, a good index is essential. Especially for locations and cities that might not clearly be in one nation or region.
I've been personally thinking of the introduction. How much information to include. Starting with a brief overview of the world (it's hook, the regions, the major conflicts) seems like a good idea. So readers can have an idea of the basics of the world without having to read the entire book. If a large part of the world is the conflict between two churches, that shouldn't only hinted at until the religious chapter of the book.
Content? Obviously you need locations and maps, important NPC's and organizations.
The big thing is the world: the nations and their histories. When the ancient ruins are found, what nation or empire they're ruins of is important to know.
Then you need player information: how the classes and races fit, any differences in those from the baseline. You also need the gods/religions. Because when the cleric player asks "who do I worship?" you need an answer.
Organizations are also handy for player motivations and hooks. Elite knighthoods players can hope to join, or scholars they can approach for information.
For the DM you need everything else. The lands and adversarial organizations. All the adventure hooks to drive stories. The NPCs and locations.
Really, if this is a homebrew world, you don't *need* as much of this. As it's created during the act of adventure creation. You only need to pre-plan the information that the players will see.
But creating a larger world is just fun.
