So, let's see how it will work when the party travels the waste, using the random tables I've made.
Right now I have a starting map, where I've filled in the most important features, and played a little bit with random terrain generation.
Now, let's say the group finds that they need to travel to a settlement three days march to the northwest of Megaton. Each hex is 6 miles wide, or quarter of a day's march (half a day's march for hills, forests and urban areas). So I'll place the settlement 12 hexes to the northwest.
The group decides to head north first, avoiding the hills northwest of Megaton. This prompts me to roll for the three hexes adjacent to their destination tile. For the northwest one I roll 64 for terrain: more hills. I roll a d6 to see if it has any features (50% chance), and get a 3 and find that it has no features. Next I roll for the northern hex: 22, badlands. Another 3 on the d6 means still no features here either. The northeastern hex is another 64: hills, and still no features. I also decide that the powerlines will continue north, and draw them in. Finally I roll for random encounter: a d6 with a 6 meaning a random encounter. I get a 2 and thus no encounter either. And the map looks like this:
Since there are still hills blocking their path, the group continues following the power lines north. Once again I roll for the three hexes that come into view, getting a minor settlement to the northwest, badlands to the north and hills to the northeast. I quickly roll again to determine the terrain by the settlement, and get badlands. Checking for features, I find that the settlement hex also has a feature, and rolling for that I get 48: Hide-away/Stash. I decide that the small collection of hovels is also an entry point for smugglers, and that they both have stuff hidden away beneath the settlement, but also in a nearby cave. Finally I decide that the power lines will end in a tangle, down by the river. I roll for random encounters and get none.
The group goes northeast to the settlement, intending to spend the night. I roll for terrain getting hills to the southwest, badlands to the north and blasted lands to the northwest. Now badlands (and hills) are just your typical wasteland environment; radiated pools, crippled trees, scattered tufts of grass, and marginally fertile soil. Blasted lands are areas directly touched by the bombs, scorched and desert-like with the occasional plains of glass. Not a place for man.
Rolling for features, I find that both the hills and blasted lands have some. In the hills there is a shelter, which I decide is a hunter's shed dug halfway into a hill, and for the blasted lands I roll a 37: traffic jam. Hmm.. I decide that on the border between the settlement and the blasted lands, there runs a minor road, surrounded by the tumbled wreckage of cars. Evacuees that were jamming the road, and got blasted off it by the pressure wave when the bomb hit.
I also get a 6 when I roll for random encounters. This area counts as the Wasteland, close enough to civilization for normal folks to live (as evidenced by the settlement), but far enough that they are still subject to raiders, or in this case: hunting tribals (as I rolled a 40 on the random encounters table). I quickly decide that they are head-hunting tribals, and that the settlement is under attack. If the group help out, they'll learn afterwards that this isn't a single occurrence. A side-quest might be in the cards.
Next morning the group travels north to avoid the blasted lands, and a special rule comes into play. Any time a new tile borders an old tile of blasted lands or radiated lands, I roll on the deadlands table. The reason for this is to create large cohesive streches of deadlands (the same principles apply to woodlands). The result for the northwestern tile is that it becomes more deadlands. The northern tile is still rolled on the badlands table, as it doesn't border an old hex of deadlands. The result becomes hills to both the north and northeast.
The feature rolls tells of some factory ruins inside the deadlands, and a church to the north, both of which are visible to the group from a distance. The random encounters roll give a result again. This time a patrol of super mutants. I decide that the church to the north is a super mutant base, and using their binoculars the group is able to learn this themselves.
So the group heads northwest, aiming to avoid the mutants, and perhaps find some salvage in the factory. Since they are moving into the deadlands, all the new terrain is now rolled on the deadlands table. In this case I also get irradiated lands and crags. The irradiated lands are just like blasted lands, except they are radioactive. Not a good place to be, but unless the players carry a geiger counter, they might not notice until they start getting sick. The crags are blasted landscapes of tumbled rocks, and large rifts. Crags do not count as deadlands, and thus new hexes next to crag hexes are not forced to roll on the deadlands table, meaning that crags will often be found at the edge of deadlands.
The features rolls provide a pre-fallout animal population in the radiated zone (12) (which I decide to change to a unique post-fall animal population: giant two-headed vipers), and the Telescopes/Windmills/Powerstation result to the northwest, which I interpret as the blasted remains of a major nuclear power station (13). And once again a random encounter. However, this time we are in Inhospitable terrain, so subtract 75 from the roll. I roll 53, which results in a negative number. So there is no random encounter after all.
Continuing northwest they simply find more blasted lands. There is feature, a hermit, which I decide is a ghoul hermit (14), who probably hunts the two-headed vipers in the neighboring hex. But the group won't actually find him unless they enter that hex.
Which they don't, instead continuing northwest. By the time they enter the hex, it is getting time to set camp. But they do see some hills to the north that look decidedly more green (well, brownish green) than the deadlands. There are no features, and no random encounter.
The next morning they head north, aiming to leave the deadlands behind. However, while the hex north of the hill will be rolled on the badlands table, both the northwestern and the northeastern hexes border a deadlands hex. And indeed it they both turn out to be blasted lands. It also turns out that there is a camouflaged bunker(15), the tumbled remains of a trailer park(17), and an operational factory(16) in each of the three hexes. I roll on the random encounters tables a few times to get inspiration, and decide that the bunker is abandoned, while the factory is being run by semi-raiders who is using it to churn out ammunition.
Tired of the desert the group crosses the river, and going across the hills and crossing the river cost them most of the day, and this is the hex they end up in by the end of the day. The result is the same as the previous hex, with two hexes of blasted lands and one of badlands. This time there are no features, but there is a random encounter. As the group reaches the other side of the river, they disturb a nest of mole rats.
And I think I'll stop here. I may already have dragged it out too long.
One obvious problem with the above is that there is no way of knowing the terrain, before it is actually rolled up. Not only would nobody in Megaton know even the fact that there was a large stretch of deadlands to the northwest, but the inhabitants of the smuggler settlement wouldn't know whether it was 1, 2, 4 or 8 hexes wide. But that's an integral weakness of the concept I'd think.