Ha I apparently missed this one.
It really depends on what favorite spot means. Is it a place to just chill? Is it where you like to quest? I will go through some of my favorite places based on different categories.
Favorite Zones: Nagrand and Howling Fjorde. It is not that I love the quests in these zones. They are OK. It is that the zones are so nice looking. They just seem nice and peaceful....dont mind all of the hostile animals walking around. Nothing to see here. Move along.
Favorite Dungeons: I think that one of my favorite dungeons based on looks and feel is Deadmines. It just has that fun Goonies feel to it. You are fighting your way through a pirate lair and come to a cave with a huge ship in it. Always a cool instance.
Favorite Hanging Out spots: Well, although I dont really ever have a chance to hang out there, I really liked the floating islands in Nagrand. As far as places that I actually hang out now, it has to be the roof of the Stormwind trade district AH. We usually stand up there a have dance parties. Before Cataclysm, one of the zones I really enjoyed was Loch Modan. Something felt very peaceful and wildernessy about that zone.
Those are some of my favorite spots in game. Where are yours?