Well, knock-on-wood, I'll be playing Swords & Wizardry with at least 2 players in 5 hours. It's been a two week hiatus since the party successfully cracked the secret of the ruined convent.
At this moment I am not prepared. I have a lot of ideas floating around in my brain, but I have no idea where play will take the party today. They have a map pointing to the tomb of St. Cecily (they don't know that's the destination), but that is a three days ride through inhospitable terrain.
Following the path the map presents should also take them by my embryonic megadungeon. It is the ruins of an ancient city built by a mad, Caligula-esque Emperor. I only have a vague idea of what they would find there if they decide to leave the trail to explore.
Anyway, I plan to firm up my ideas on random encounters for the hills they'll be riding through. I will rough out the caves at the end of the map, assuming they plow through the wilderness and make them. I'll also prepare some specific encounters for a hill giant and a patrol of a tough, pony-riding, hill people I have in mind.
One thing I'm realizing about wilderness travel: it's hard to give players choices without specific landscape details. I'm wondering about the legendary Western Marches campaign, how specific did the DM get in his descriptions of the land they were travelling over? Because if you don't have something like a crude topographic map, it is all a hazy, vague area to be moved through where ambushes can spring from anywhere. Maybe this is why wilderness travel is often handwaved to get the party to, and into the dungeon.
I want to give the same sense of adventure and danger that the party gets exploring dark, underground passages for their journey through the wilderness though. I'll see what I can come up with and pay close attention to how it plays out.