Now, mucking around with features has brought something to my attention. Let's suppose that we take a simple hex, 20 miles in diameter, without any major water course and without any significant town or village. This can greatly reduce the number of things that might be present.
I said no 'significant' town or village ... we still have to reserve the possibility of insignificant hamlets and such. A typical manor property of the medieval period would correspond (generally) to the following English-minded image (which I'm stealing from my own site, where I posted it in March of 2010):
Farms, forest, meadow for livestock, a small village, a blacksmith, a mill, toll bridge, church, parsonage, church or chapel, manor house. For the hex I'm proposing we can toss out the mill and bridge, since as I said, no sizable watercourse. Somewhat higher country, a few streams too slow to run a mill and with too many fords to bother bridging, etc. The blacksmith is debateable, but for simplicity's sake, let's say no industry.
There still might be a hamlet, with or without a manor. There might be a castle, even, particularly if it is a border hex. A hamlet might contain, with no guarantees, a chapel, a well or a guard house. It might be organized around a mine, saw pits or a quarry, and it might be defended by a palisade. There might be a barn, but probably not a stable.
If you were passing through a hex that was 20 miles across, how would you know it was there?
Here's something that I've been thinking about has to be part of filling the hex: signage. There would be some kind of sign telling the party that there was a hamlet, and pointing at where it was. Now, this is the sort of thing I've more or less taken for granted, but there's a lot to be gained from a sign. For example, I've been thinking about the difference in ponds that are empty of fish and ponds that are actually quite good for fishing. The latter would be a boon to a party ... but unless you sit and fish, you can't tell the difference, right? Well, there's the kind of Natty Bumppo trick where the ranger just looks at the water and knows, but that's really kind of crap.
But a sign! A good fishing pond would be named, because people like to name things. Moreover, the party probably wouldn't just come upon the pond and see a sign in front of it ... there'd be a sign four miles away that said, "Bumppo's Pond," with an arrow pointing along a path.
A sign for the hamlet over the horizon might well include some notation that of a quarry or a mine ... the name of the hamlet itself often indicates things about a town: Fishersville, Watch Hill, Hartford, Plainfield, 'Virginia' Beach, etc. In modern parlance these names usually don't mean much (is there still a 'ford' in Connecticut where the capital is?) ... but in medieval times, these things were exactly what they said on the tin.
The signs should be there. Not just the usual no-trespassing, but signs describing gaps between hills, bogs, roads, meadows, camps, churches, hills, beaches, coves, bridges and so on ... not just where those things are, but at crossroads and turn-offs miles away from where those things are. So that a party walking along a road isn't in a vacuum, they're beset upon to make up their mind to continue straight ahead or to check out the 'South Meadow Great Cedar Swamp' ... only to find out its an 800 foot-wide wetland.
What a disappointment.