My favorite GF run with a dh is nightmare heart of sin.
Start on the 'The second heart'. Go to arreat crater lvl 2 (second to last wp available). Run through the whole thing, kill spider, then to azmodan. Once i got the run paths down runs are just under 10 minutes. 35k gold. I stopped picking up most items, but will pickup rare armor/jewelry, it is all level 40-48 stuff. It generally sells faster then bad 60 gear you could be getting in inferno. I usually find 1-2 pieces worth selling a run and price it at 20-30k.
Pure gold it is about 200-250k an hour.
I run 178% gold + 10 ferrets + neph buff. Gear is just lvl 56+ gold find + dex gear i could find. Spent about 200k 2 weeks ago, so its probably 600k gear now.
With the current prices of useful lvl 60 gear i don't think it is worth it anymore unless you need a small amount to get over a hump.
I run from the last "teleport waypoint" to the entrence of azmodan, than leave and start again. You will spawn on the other side now (directly at the entrance to azmo) so you dont have to tp from town it nets between 5k and 15k in 2min (~250% mf) with an average of about 8k --> in 1hour you get about 200-250k. I only run that part since it was recommended by a friend (who i later found out is running a bot so it might be more profitable to run the second heart to azmo)
But all the same the question of where the most populated areas are is interesting for leveling with massacre xp boni did anyone make any observations?
I prefer a longer run in a high density area because it's a longer time with 5 stacks of NV, which I think would make for more ultimately more efficient GF then just doing 5 minute runs of the crater x a billion. I should prolly do some testing to see if the facts match my intuition, but I think it'd be marginally more interesting at least.