After reading about half the posts, they all started to sound about the same.
In all seriousness, if you want the population spread out, why do a lot of the non-multiple city portals eventually lead back to SW/ORG?
MOP Honeydew portals: Pandaria to/from SW/ORG
Dalaran portal: Dalaran to SW/ORG
Blasted Lands/Dark Gate portals: Major cities to Blasted Lands, Dark Gate to SW/ORG
Darkmoon: Darkmoon to/from outside SW
Cataclysm portals: Wherever to/from ORG, with the exception of from Uldum and Therrazine portals
One exception is the Horde Darkmoon portal to/from TB, and traffic does pick up in TB when Darkmoon is around. World events that send people to other major cities also seems to encourage travel and spread out the population.
Portal hopping does get really annoying and it really doesn't do anything to get me "out and about" since I repeatedly use the same paths. For example, I will often travel through the Blasted Land/Dark Gate portals to get back to ORG, but I don't ever stop there. I kept my Kirin Tor ring, so CDs aren't really an issue for me, but it is a bit of an inconvenience to have to lose a bag slot to it and to occasionally forget to re-equip my geared ring. It does detract from the game.
Blizz: People have their favorite cities, maybe because they like the theme, the layout, or other random reasons. When people all get shunted back to the same cities (SW/ORG) all the time, they get used to it and forget those reasons. If you want people to be out and about more and spread out, do some traffic pattern analysis on your servers for where people go during what times and figure out why. Try out having more portals or shift the portals back to other major cities on your beta servers and see what people do. Try putting portals to all the cities to each other, and then give each city unique characteristics that would draw different interests. Or let mages put up portals that anyone in that faction can use, and that stay up for longer periods of time. Maybe different PVP or pet battle mini arenas with rewards unique to those cities or other incentives, including rotating the location of the Darkmoon portal to other cities, and more world event quests/tasks that send you to different cities, might help.
EDIT: Ha! I didn't even realize you can't reforge or transmog other than in Two Moons, Seven Stars, ORG, or SW. Goes to show how much we are shunted back to SW/ORG.
Edited by Loranta on 12/5/2012 6:49 AM PST