Dangruf Wadi - The only time people really come here for the most is for certain quests... THF AF2 being the top one.
Oldton Movalpolos - Lots of miners here, as well as peopel camping some Bugbear NM.
Carpenter's Landing - People camp Orctrap all the time. Not to mention BSTs level here from time to time.
Outer Horutoto Ruins - BLUs come here to learn Bludgeon, and people on Windy 6-1 or 8-2. Other than that, pretty empty most of the time. XD
Ranguemont Pass - Always people going through here to get to Beaucedine rather than getting a Teleport-Vahzl and walking from there.
The Base of Drachenfall (Absolute Bottom of North Gustaberg) - I see fishers here pretty often on the rare occasion I come here. Also, a THF AF2 mob is here, and so is the Siren's Tear needed to flag BLU (if you get assigned that item instead of one of the others).
Giddeus - People harvest a lot here, as well as farm Yagudo Necklaces for Norg fame. Also, Hoo Mjuu campers are here like 24/7.
Yughott Grotto - Lots of miners here, and some fishers. Also people camping Ashmaker Gotblut.
Ghelsba Outpost - Very common area for people to level in the solo levels.
Fort Ghelsba - Much less common than Outpost, I must admit. Don't often see too many people here.
Gusgen Mines - *Always* plenty of miners here. Also BST levelers, BLUs trying to learn spells, people farming Magicked Skulls for subjob quest/Aht Urhgan access, people doing their RSE... you get the idea.
Ordelle's Caves - Morbolger campers, as well as people doing RSE.