I like to go out and pose riddles to unsuspecting lowbies. If they're answer is good, they'll be rewarded some gold! But then I vanish with a Potion of Deepholm, makes for a grand exit.
As a result, mine is set to random low-level areas. Whatever ambience feels best at the moment.
As an Alliance mage, Uldum, because you have to go through 2 loading screens and fly through the whole Stormwind to get to the portal.
I had in Mechagon before, but since I basically only travel there for when the Call to Arms happen, there's no point anymore.
To me, Uldum is worth because is a place that we have to visit every single day for the sake of dailies. Thank goodness Vale is covered by a teleport spell.
I'm actually baffled that the two 8.3 content zones doesn't have direct portals there.
Rustbolt Resistance
I can get everywhere else rather quickly Rustbolt is the only area that doesn't have a portal or some sort of transportation attached, plus its convenient as I still am trying to get mounts from there.
Uldum.
Because anything else is a waste of HS.
Atm in Uldum and otherwise somewhere desolated
Orgrimmar. That way I have access to the main teleport hub there and then take 1 to zandalar to get to the other lot. Incase none of you genius minded people who keep saying Uldum didn't know. There is a teleport to Uldum at the Cataclyscm hub. Just FYI