Originally Posted by
Naughts Skyway
^That.
Thunderbluff and Undercity are much more convenient for practically everything after the recent changes (mailbox movement in UC and staying mounted in that TB Cave after ports), except for PVP rewards. Thunderbluff has to be the best by far with auction house, bank, mailbox and forge practically touching each other. The only time I ever go to orgrimmar now is to buy honor gear. Silvermoon is very convenient once you know the place, with it pretty much being two cities in one. (it has two+ of -everything-. All of the profession trainers have auction houses, banks and mailboxes right next to them.)
But most people just flock to Orgrimmar out of habit and have no intention of sitting in a city by themselves.