I’m using the Nentir Vale, a 4e setting, as the basis for my campaign. It’s FOE af, but I have yet to find another map as eminently usable for adventures, outside of Mystara. And I don’t want to log the hours required to draw my own digital map. This is one of the hidden bonuses of theatre of the mind; it lets the GM be lazy.
I was going to use the outdoor survival map, but I couldn’t find it in a decent enough resolution for a VTT, which would mean that I’d have to draw it myself anyway. If you turn all of outdoor survival’s ponds into towns like Vol 3 suggests, then suddenly the map is missing some important geographic features. It also doesn’t have a tundra zone or a border with the sea, so those elements would have to be added in, and it has two deserts. The Nentir Vale is similarly land locked, and it doesn’t have any deserts, so it too needs some expansion.
The provincial maps of Mystara, such as Karameikos, Glantri, Ylaruam, Alfheim, etc., are perfect for adventuring. My only issue is that if I were to use them, I’d try to do them justice by playing the whole setting as is, and I don’t actually want to do that as I have a lot of home brew setting ideas that I’d like to implement. I particularly don’t like the idea of the Immortals as the deities of the setting. I think they’re a neat endgame for PCs to reach the heights of power, but I prefer actual gods to be the creators and maintainers of their universe.
Greyhawk is not really usable as an adventuring map. It seems built for war game campaigning, where whole armies would move across it at the rate of 1 hex per day. All of Gygax’s publications seem like sketches that require the individual to fill in all the pertinent details, and the World of Greyhawk is no different. There’s a sparse few capital cities and large tracts of empty wilderness between them, meaning that all the villages, roads, natural features, and dungeons would have to be filled in by the DM. The officially published TSR adventure modules are scattered randomly over the map, making no logical way to connect them geographically without the PCs traveling for in-game months to reach them.
The map of the Central Flanaess that came with the City of Greyhawk is at a much better scale for adventuring. It’s kind of bland and the adventure book is a mess, but it can be fixed with a little work. It is also a natural area to fit classic AD&D adventures around. Hommlet and the Moathouse can be moved to the region at the foot of the Cairn Hills, and Nulb and the Temple of EE can maintain its relative distance from them in the hills proper. The Lost Caverns of Tsojconth and The Forgotten Temple of Tharizdun can be relocated within as well, and the Slave Lords series can be moved to the south shoreline. Only the Giants series is a bad fit, since they imply wide territories for the giants, but the modules are actually just bare dungeon crawls and there’s teleportation between them, and of course the Drow modules are subterranean.
Making the eponymous City of Greyhawk the geographical center of the 1e adventures seems thematically proper to me. The actual adventures that came with the 2e boxed set and the big meta plot campaigns that followed are not really good.
And the Forgotten Realms is like, the worst campaign setting.