After running The Glittering Caves for the second time, I thought a map might be helpful, so here's my first stab at it. Not to scale, just a rough layout of where things are.
Can folks help me with missing items? Kinnies have filled in some of them, but locations for some of the side quests - Bombs and Bats, Cave In, and Preparing the Charge - need verification or clarification (e.g. where exactly are the bats?). I know there are multiple crystals, but I only marked the Spider Assault one; if there are others that need to be protected or interacted with, please let me know. Thank you in advance!
Edit: Side quest locations confirmed, uploaded corrected map.
Notes: When in the Helm's Deep "Before Dawn" instance for Volume III Book 13 (accessed using the barrel near Gleowine), the portal to the caves is located north of PC. For the final assault, Gamling and Gimli move to the central positions marked as “Gamling 2” and “Gimli 2.”