I go along with the JTAS entry, with 7 hexes on a triangle side = a size 7 world. So the diameter is (5 x world size) hexes. A size 7 world has a diameter of 35 hexes = 7000 miles = 11,200 km, so there's 320km to the hex.
Checking my math. A size 4 world would have a 20 hex diameter, which means D = 6400km, or 4000 miles. Yep, that's the scale I use, all right.
Note that in my samples, world size 8 still doesn't quite fill its allowed space. A size 10 world would fill it up entirely.
I think I'd take your advice and use the whole sheet for the world map, separate sheet for system data.
I'd probably use size 10 maps for size 11 and 12 worlds, if only because they're rare. Size 12 worlds and up are likely to be panthalassic anyway, in which case there aren't really any features to model, except for exceptions of course.
Checking my math. A size 4 world would have a 20 hex diameter, which means D = 6400km, or 4000 miles. Yep, that's the scale I use, all right.
Note that in my samples, world size 8 still doesn't quite fill its allowed space. A size 10 world would fill it up entirely.
I think I'd take your advice and use the whole sheet for the world map, separate sheet for system data.
I'd probably use size 10 maps for size 11 and 12 worlds, if only because they're rare. Size 12 worlds and up are likely to be panthalassic anyway, in which case there aren't really any features to model, except for exceptions of course.