I am currently lvling up a Spriest alt just to run some Naxxtwinkraids. I dont want to do those brainfucking WotLK quests again - so I am looking for a way just to grind it up to 80.
just do the quests again - you'll remember half of them already and there'll be much less people in the zone than first time round so you'll do them much more quickly.
If you really want to grind mobs all day (probably using a bot) Go for the animal packs. Theres tons in every zone. Once you hit high enough level to go to Storm peaks you can farm some descent rep items worth about 4g a piece on my server.
download carbonite quest addon and just do the normal quests. way faster then brain-afk mob grinding all day long.
and also mob grinding wont give you any new items while lvling up.