After getting lost time after time the first time I went into the Pit, I went back in and explored the ramps in more detail. Turns out there's a fairly simple layout with 4 branches from a central node. Here's how I find my way around now.
1. Find the 'central intersection'. This is the junction where you can walk to either the north or south spiral, and there are ramps both up and down on each side. There is a force trap pillar in the middle of this junction.
2. There are four directions you can choose from this intersection. After leaving this intersection, there are almost no other branching points -- you can simply keep following the ramp (as it moves back and forth between the two spirals). Starting from the intersection:
North column, up ramp: Breaker Room -> Acid trap* -> Backup Generator
North column, down ramp: Bilge -> Furnaces -> Main Control Room -> Shrine
South column, up ramp: Entrance -> Security -> Intake
South column, down ramp: dead end
*- the only other 'branch' is a fork off to the left of the acid trap which leads to a dead end ramp.
Jotted this down for my own benefit, but figured others might like a more functional 'map' too.