I just want to reiterate something I said here before.
Make rooms easy to describe.
Seriously. My players went back to a section of the first level I drew in my earliest mapping of Felltower. It's maddening to describe the rooms. Big odd shaped rooms, strange turns, odd intersections, weird room locations, etc.
We took up over half the session in that area, and while that was fun, it was also because mapping it was difficult and describing it took a lot of excess words.
Had I used a much simpler layout, it would still have been a nice area of dungeon, but not such a pain to describe. Using words to describe what you see is tough - I'm trying to reduce what would be visually interesting but not especially difficult to understand with words that just aren't quite up to the task.
Add in a new player mapping because the veteran couldn't follow my descriptions and voila, half a session spent on what could have been more easily done in 30 minute with rooms that were easier to describe.
It's not an especially fun part of the challenge, either. That's why I'm saying it again - it doesn't have to be hard to describe to be hard to navigate, or crazy to draw in order to be exciting.