When I tried out WoW after years of EQ, I thought their scripted flightpaths were one the most awesome new features. Flying over dangerous areas that one day you may get to visit, seeing actual players on the ground doing their thing, high level creatures that roamed far below you.... . I also loved the scripted horse rides in DAOC for the same reason, so I guess that feature really sits well with me. EQ2's could have been nice were it not for all the hitching and stuttering and horrible clipping during such a flight.
However, I am not a fan of freeform flight and am not a crazy fan of Mounts; I would love to see dedicated teleport classes again and boats (maybe this time with something to do on them). I think both Teleport classes as well as scripted horse/flightpaths can go well together. And in a World without mounts there would also still be a place for runspeedspells(though SoW was so much more in EQ: it was like a "save your bacon" spell which in turn relied on several other game-mechanics like deathpenalty and corpseruns).
All in all, I am a proponent of the feature that convenience should be earned over the levels, being part of the road from Rags to Riches. WHen playing EQ, I do not oppose to the PoK portal stones anymore, because after playing 14 years (on and off) I feel I have earned the right to travel the lands (i.e. 450 zones and 20 expansions) in such a way.
So next to scripted horsepaths and teleporting classes, you could give high level players access to certain portal features, preferably with some variety and in tune with Class and Racial Lore. I.e. not some generic "Everyone gets to teleport everywhere at level 50) but rather stuff like the Firepots(tucked away in some high level zone), clickies with a single teleport location on cooldown, expensive potions, extensive Quest opening up a few portal locations, you name it. I realize that this is a LOT of work though, it is off course much easier to develop a single system for everyone and be done with it.
My advice fro Brad would be to keep it lean and mean in the beginning, then work from there. Off course if he wants people to be able to instantly group up together so they can do a dungeon, then discard all this.