This page at World of Warcraft Pro has maps for getting to Thunder Bluff. It's explaining how to get to Thrall (isn't he in Nagrand now?), but the map would likely work for us too.
Getting to Him: Have your raid assemble in Astrannar, Ashenvale and then ride the road east and then south into the Barrens. From there ride east along the northern Barrens until you reach Orgrimmar's side entrance. The goal is to take the significantly less guarded side entrance that leads directly to Thrall's room.
There seem to be many more flight points closer to The Gate now, like Fort Triumph, below, but I guess I'll hoof it from Theramore, since I don't have any of those flight points active/discovered.
This will be much easier in a week, when we can get to level 85, throw gold down a gold sink, and fly around the Old World.