This is an important question related to the game at large, what will be the size of a normal map in the game?
If all of the game world was placed in one map, with perhaps additional dungeon maps, we would have a large open ended world. Many modern western RPG's are like this. Oblivion and Fallout most notably. It's a good choise for real 3D worlds as you need to see farther than you can walk anyway. But to me there's usually always too much walking around, too much nothing in between things. I'm envisioning Driftmoon a little more tight packed. Technically it would require a lot of changes to get everything to play smoothly on one map, so I'll have to rule this one out by lack of development time.
A medium sized map could have one town and various open areas- a lot of quests to play with a reasonable amount of enemies. Something you could spend an hour or two playing. This was my original plan for Driftmoon, and each map would have been an island. You would have played the islands sequentially, and within the island would have been an open area for you to play as you like.
But the more I think about it, the more I would like to play in even smaller areas. Even on a medium sized map there would be a lot of boring walking around, fighting filler enemies. Basically all RPG's tell you at some point that here's somewhere you need to go, look it up on your map and get there. That forces you to leave areas unexplored, or if you decide to explore everything in your current location before going to the new place, you'll likely forget the plot, why you were even going there. That happenens to me often, I decide to explore the current area completely before going on, and then I drop out of the main plot and quit.
What I've been hatching is bite sized maps. They have one main quest, maybe one optional quest, and a couple of enemies to kill. Each area can be as unique as I like, they don't have to be connected to each other by filler terrain or filler enemies. When you're done playing the area you really know that you've played it through, you don't have to spend 10 minutes looking for important people you've missed, main quests you're missed. You can play it in one go so you're less likely get interrupted and forget what you were doing. And even if you do get interrupted, the map is small enough for you to find out what's going on.
And if you're anything like the people who've test played Driftmoon when I've been looking, you'll be very glad that a smaller map is easier to navigate. All my testers got lost at some point in the preview maps. And those maps were pretty small to begin with!