I did indeed change to describing the mines rather than laboriously drawing them. One of the two rooms I had to draw, because there was combat in it, I simply could not get right, no matter how carefully I copied my original map, so eventually I gave up and called it good enough.
Two other highlights in this session:
The random encounter table turned up 1d3 horses deep inside the mines. Keep in mind, these mines have been infested with giant centipedes and abandoned for many weeks. In retrospect, "you come upon three horse skeletons" would have been a much better solution - the random encounter doesn't necessarily have to be alive, after all. Instead, I betrayed the principles of the random encounter table and said "No, that's preposterous, I'm rolling again." Alas.
The other highlight is a completely unpredicted situation. One room contains an empty barrel, which I decided on the fly happened to have been filled with some kind of booze at one point. One player figured the barrel, soaked through with old alcohol, is probably super-flammable. So he picked it up, carried it until there was an opportunity to use it, lit it on fire, and rolled it down a tunnel into the next room.
At which point I noticed my map key for the next room read:
northeast corner is shored up with extra supportsDue to the layout of the corridor, the barrel was aimed directly at the northeast corner of the room. The wooden supports merrily caught fire.
The PCs fled the suffocating smoke and angry swarm of centipedes. When they return, they're likely to find that room has quite collapsed in all sorts of interesting ways, for the same reason it had that extra bracing there in the first place.
The fourth game, I tested out the "cantrips/orisons as a free action" rule, and introduced the gladiatorial arena. I was secretly hoping the players would pick the arena, because I was a little excited to try it out, and, happily, they did. All the players but one brought their own characters, which is good.
They went through Round 4, then one of them had taken some poison, so they took their winnings and went home and slept for three days and came back and went through Round 5. Which is pretty impressive for level 1 characters, though they got lucky on the second go through, they got a First Blood match in round 4 against a single earth elemental. Which was a good combination, as earth elementals have quite high AC for that level, but somebody still rolled really high in the first round and took it out.