|Map of the Dawnlands|
I did this by hand in 2009. I've been tempted over the years to update it using Hexographer, and turn it into a keyed hex map. I never have. The Dawnlands setting doesn't have maps in-game, so it would be purely a document for DM use.
In favour of a keyed hex map:
It would allow me, and anyone else who wants to use it, to unify the descriptions of navigation given by people in the Dawnlands with meaningful landmarks. Like, say your PCs want to get from Butcher Hill to the Cyclopean Barrow because it's the lustral gathering of the Kadiz clans. Instead of having to go "Uh, ride north a hundred kilometres and then go west" (which is impossible to navigate by IRL, let alone on the plains) you'd be able to check the hexes on the expected path, find the landmarks in them, and then tell PCs "Ride north until you hit the geyser field, then go north-west until you see a grove of pine with two boulders on the south side, then..." and so on. The advantage of having these set by a keyed map and reference document is that they would remain consistent, instead of me having to make them up or handwave them.
As well, I've been thinking of writing up and one day publishing some of the Dawnlands material as an Openquest supplement. The map and reference document are part of that plan, and having a keyed hex map would allow me to present information about the setting without having to descend to pompous and vacuous thematic statements like "The nomads of Kadiz roam the wastes" - I'd just put the Kadiz nomads all over the place.
I use hexes with 5km apothems, and the area to be covered is 323,500 km^2, which means I'd need around 3736 hexes (calculated using this tool) to cover the area, though that counts the ocean, so I might be able to slice off a thousand or so. One possibility I've considered is going for even larger hexes, with subhexes within them - probably hexes with 30km apothems, which would only require 103 hexes for the whole area (counting ocean again). Each super-hex would then be broken down into a row of twelve smaller hexes of 5km apothems, and so on. While this is appealingly possible, my main concern would be knitting borders together.
I'm unwilling to reduce the size of map any further than 500km x 632km because I've already reduced it - it was originally 1000km x 1294 km (for a massive 1,294,000 km^2, about six times the size of the island of Great Britain). As it stands now, the Dawnlands is about half the size of France, which gives me a good range of climactic variation, as well as a population that is large enough to support two large cities while still having room for lots of sparsely populated wasteland.
Keying the map would also involve filling in everything, which I'm worried would make the setting less interesting for other people, since it would be more difficult for DMs to "own" it. For example, Forgotten Realms used to have areas that were purposefully left blank (the nation of Sembia), so that DMs could put whatever they wanted in there. There were occasional references to things in there, and the border of the country was outlined, but that was it. I remembered being tremendously disappointed when I read the 3e Forgotten Realms and discovered that now Sembia too, had a canon of importance places and person to be memorised and regurgitated. I want to avoid that with the Dawnlands.
Finally, and this may seem an initially trivial point, if I were to make a keyed hex map, I would have to use non-standard terrain types, which would make it even more difficult than filling in 3736 hexes normally would be. For example, a huge chunk of the Dawnlands is plains, but different kinds of plains. Under a standard marking system like the one Hexographer uses, these would be plain green, or they have a little grass-plant like design, but that's it. Plains are plains are plains. But of course, plains are not plains are not plains. Chalk heath is different from karst and alvars which in turn are different from moors which are different than prairie and steppes, to avoid getting too technical, because the differences between those four terrains (all of which occur in the Dawnlands) are exceedingly important to the pastoral nomadic groups who PCs are expected to be drawn from.
More than that, knowledge of the different types can drive stories. For example, the predominance of karst geography in the southern-eastern plains means that water is scarce, and often involves exploring limestone caves to find underground rivers. Access to the main aboveground river (the Last River) is a major sticking point and leads to fights between the Kadiz clans when one group denies another, or pollutes the water source. Plus, there's a type of ghost - the orvanshur - that is more common down there because it's created when someone drowns at the bottom of a pit. The other terrain types create their own challenges in turn for the people who live on each.
At the very least, I'd want to mark out karsts, chalk heath, steppes / prairies and moors from one another on any detailed map I did, but I've yet to find a notation for these that satisfies me without being overly complex. If I do decide to create the map, I'm thinking of buying a pack of pencil crayons, doing the whole thing manually, and using varying amounts of grey and brown over a green base to indicate them, but if anyone has a better idea, let me know.