As I'm world-building, using material from all campaigns and modules I masterised from the last 27 years, I had a look on a few classical world maps to try to catch what's the spirit of a good world map. Here are 5 of them, but I could add more based on the same principles : Blackmoor, Wilderlands, Greyhawk, Known World and Forgotten realms.
The first feature which strikes me is that none of them is a full world map. Borders are mostly lands, not sea, as an invitation to go further. Unfinished maps for unfinished tales. What's south of Blackmoor ? What's West of the Wilderlands ? The DM's imagination...
I guess this feature comes from earlier fantasy litterature. Middle-earth, Hyboria, Newhon or Young Kingdoms map are based on the same principles.
I remember my first attempts of world buildings as a young DM. As far as I can rememebr, I nver played in tose big continental maps I drew, while I can distinctively remember I used smaller, unfinished ones, as seetings for my games. maybe i'll post some of them here soon or less.
Another striking feature, of which Blackmoor is the best - and earlier - example is the idea of the Great bay: sea goes faraway in the lands, like a Mediteranea. In these five maps, only Known World escape this feature. All have a big surface of seas.
The 'Great bay' feature had a significant impact in my longer D&D campaign, with the CM1 'test of the warlords' Norwold's Great bay aera. This module's map share's clearly tehse two features: it's organised around a great bay, with land on two borders of the maps.
So... my current world-building work-in-progress has still no map, even if the picture is growing in my head. Now, I think I found two clues about how organize it for a mysterious, successful map.