I imagined something like this. The description also mentioned
that there were rows of windows glowing with an unholy red light.
The map was divided into three parts, representing the three internal levels of the stronghold - the large top floor where we entered (the top of the stalactite), the smaller middle floor where the end of the encounter played out, and a tiny lower floor that lead to the exit. Below the stalactite, a giant web acted as a safety net... just kidding! Anyone who fell off was going to get chomped by an enormous spider. And since it's D&D, the only paths between the levels were on the outside. Drow engineering at it's finest.
My table ended up staying waaaaaaaaaaay past the usual time, for a couple of reasons. First of all, we had two newbie players - like, "played once in my life" newbies. Secondly, the DM wanted us to help them level up their pre-gen characters. It was a nice intention, but in the end I think it just made things more confusing. The biggest reason it took so long, and this is an unfortunate possibility in D&D, is that we were all rolling complete crap.
Speaking as a DM, it's hard to know what to do when your players - or even worse, just one of your players - is consistently getting terrible dice rolls. There are some mechanical "fixes," like Heroic Effort (which lets you add 4 to your attack) and Elven Accuracy (which lets you re-roll a terrible result), but not everyone has them and they're only good for one use per encounter. In my home campaigns, I've instituted the Nightly Re-Roll - anyone can re-roll once per night. On one memorable occasion, they were doing so poorly that I allowed them one re-roll per encounter. If a player is really close to hitting, I might have them roll and Athletics or Acrobatics check as a minor action to "help guide their attack."
Usually, however, I try to do things "behind the screen." You don't want to seem like you're being too easy on your players, so as not to cheapen their victory. Sometimes I'll forget to use a monster's regeneration power, or I'll neglect to recharge their most badass attack. That's why I hate players who try to sneak in a re-roll or add bonuses they shouldn't have - there's no need to cheat! Mama's got this.