As far as dungeons go:
Ones to avoid:
- Occulus. You'll have to bind the drake keys and it's a bitch to keep the characters following. Also, lazyboxer won't use the drake abilities correctly, so you'll have a heluva time killing the last boss. If you make it that far, I commend you. I'll never try this dungeon again.
- Vortex Pinnacle. The first and last boss will destroy melee classes. Jumping between bosses will make you have to stop the bot, move the characters to the next tier and then start it again.
- Trial of the champion. Another dungeon with mounts. The first boss is a nightmare once again.
Ones that have issues:
- Blackfathom Depths. The water here gives the bot fits. If you're going to do this dungeon, just skip quests and head to the last boss.
- Blackrock Caverns. The first boss will cause wipes. Try and move at least your healer and tank away from his spin attack or your gonna have a real tough time.
- Halls of Origination. High movement fights that will cause wipes. Easier to just avoid this dungeon.
- Grim Batol. If I do this one, I avoid flying the drakes at the beginning, or just fly the drake on one character to get 1 bombing run in and then kill all the packs. You'll have to stop the bot again to do this.
- Scarlet Monastery - Cathedral. It's tough to get good pulls after the first boss. You may end up pulling 3-4 packs of mobs together and end up wiping. Second boss can kill your group quickly if they stay clumped up. Inside the cathedral, you may run into mass pull issues as well.
- Sunken Temple - The priest boss will wipe you if you're unlucky. If you're tank gets charmed, all characters will stop working and your tank will kill them. More wipes caused because of this than any other boss.
The perfect leveling path through dungeons that would give the maximum leveling speed, but would take some luck in getting through randoms:
15-20 - Deadmines, You should get 5 levels in a single clear. Fast and easy, but you may have character die due to lack of gear and lack of aoe abilities on your tank.
20-26 - Shadowfang Keep. This should take 1-2 runs, if you end up doing 2 runs, you'll probably end up above 27.
26-32 - The Stockade. This is the second best leveling dungeon due to being able to skip all optional bosses and can go straight for the last boss. Can clear it in less than 4 minutes if you're good. Each run should get you at least 1 level.
32-36 - Any of the Scarlet Monastery Dungeons. Although I mentioned that Cathedral has issues, it's also quick, has good loot and good xp as long as you can avoid wipes.
36-40 - Maraudon - Earth Song Falls. Good, quick dungeon
40-44 - Uldaman - Same as above, not too difficult of pulls and lots of quests
44-47 - Zul'furrak - Same as above.
47-50 - Blackrock Depths - Detention Block. The fastest dungeon to clear. Kill the first packs, head right, go through the center, kill last boss and start over. Can be done even faster than the Stockade.
50-55 - Sunken Temple - Fast clear, good loot and a trinket for a quest. The priest boss will wipe you though if you're unlucky.
55-60 - Lower Black Rock Spire - Fast easy clear.
60-70 - All BC dungeons work well. Just finish one, queue again and continue on.
70-78 - Keep doing randoms. At 78, stop random and choose Utguarde Pinnacle and/or any of the Frozen Halls dungeons in Icecrown. I usually check all 4 and see what I end up with.
80-82 - Buy loot and you're going to get end up getting Throne of the Tides and/or Blackrock Caverns 5-6 times to get to 82.
82-83 - Any random will do
83-85 - Lost City of Tol'vir or Grim Batol. Grats on 85 in around 24 hours played time.
I try to do most dungeon quests, unless they're gathering quests. Thankfully there's really only a few gathering quests throughout the dungeons.
Whenever possible, it's always faster to skip optional bosses and just head straight to the last boss (unless there's quests involved). Especially at lower levels. The bonus xp for completing a dungeon is really good and the bonus packs you get at low levels contain good loot.
I could probably give tips on every dungeon, but I'm not going to. There's mechanics you'll run into that will kill characters now and then. You'll run into them yourselves on your way to 85. The tips above alone should greatly help with leveling speeds.