I'm slowly working on a wilderness sandbox for my players. Just the foundation for now. A couple thoughts:
I want to make this as simple as possible for players, like a gameboard, so I can start specifying options and features in the wilderness. I was thinking that it's funny that 4e spent so much time trying to simplify and specify D&D's abstract combat, but, as far as I know, ignored wilderness travel, which has always been super abstract. Combat never seemed all that problematic to me. I mean I can pretty much imagine what the results of a few rolls mean for 30 seconds of fighting. With abstract wilderness, though, you gloss over travel through 5, 6, or 25 miles in a hex, you're missing the whole movie!
Related to that, I was realizing how the default unit for D&D wilderness seems to be the hex or sometimes the kingdom. I'm thinking a much better unit to work with is terrain, and treat the terrain almost like a very large dungeon level. My last post was my first steps toward that end.
I've actually grown to dislike hex maps because I associate them with these huge tracts of abstract land with little help on how to run what's in them. And numbered hexes seem very futuristic to me, perfect for Traveler but not the right tone for a fantasy setting. Because of this, I was going to try to avoid them altogether and use roads marked out with distances sort of like gameboard spaces. But I want players to be able to go off-road too and have an idea how far they can travel through a forest in a day. So hexes are unavoidably, really. I'll try to keep them grey, just visible enough to see, but not obstructing the look of the map.
So, I think I've settled on hexes that are 1 inch wide on the player map and 6 miles in game. I want the hexes big enough on the map to have images of landmarks that players can see as a group. Not just one person squinting over the map. As for in-game, you can see this old post extolling the virtues of the 6 mile hex. I also like that these will work better with leagues. So I'll actually be treating them as 2 league hexes. Leagues, like stones for weight, are good because they make the numbers we're working with smaller and they're also evocative of an older time. They are also handy because human walking speed is about 3 mph so you can say every league is an hour of walking.
My desire for simplicity wishes that the hexes could be one league each, but it would make the sandbox way too small. Players could walk out of it in two days.
Let me back up a bit. I'm going to assume folks can walk 6 leagues a day. That's a bit low, but I'd rather err on the low side than on the high side. And keep in mind, even on roads, the terrain is probably rough, overgrown, and requiring a constant watch for hazards. This will also let me simplify horseback travel by telling players to double their number of hexes they can move. Again, 36 miles in a day on a horse might be on the low side. But another reason to keep them low is that I can simplify forced marches by just saying double your hexes. So, 72 mile for a horse being pushed is within reason as is 36 miles for hikers.
I started out with four letter-size pieces of paper laid out in a rectangle. But that was too small. So I upped it to 3x3. With rough terrain slowing folks down a bit, even on horseback, it should take more than a week to get off map. It also isn't too big to have on the table in front of all the players.
I don't want to constrain the players to this sandbox, but if I'm going to put work into making a lot of locations they can visit, I want it to be of a size that they can't just ditch it all in one session.
Hmm, I don't know, I might still try to shrink the hex size to half an inch and make them 1 league each. Then I could have small icons representing landmarks but much larger images along the margin of the map like the last example here. I suppose design isn't finding the perfect solution, but the best compromise. I'm trying to balance simplicity of communicating travel rules to players with them having a map they can see and not walk off of in one session.
Building on the Foundation
If I keep it simple it should be easy enough to add complexity on top of it. So, traveling through rough terrain could halve your travel distance and traveling through some terrains in winter could halve it again. Special breeds of horses could add a hex to their travel distance, or only in certain terrains (stout ponies in hills) or seasons (shaggy tundra horses).
You might even decide a certain speed rumors/news travels across the map in hexes. So, if players keep getting hirelings killed, for instance, the next village may not want to see any of their offspring hired.