Yes, I used that dirty word "grinding" -- sometimes there's no way around it. MMORPGs are time sinks, and WoW is no exception. Well, in the case of tailoring, the Burning Crusade makes a bit of a grind worth the effort with the introduction of several epic cloth sets. In addition, there are three complimentary sets for each, the patterns for which are drops. There are also several non-set cloth epic patterns. If you aren't already familiar with them, get on over to wowhead and check them out.
My mage was a miner/skinner before Burning Crusade came out, so I've had to power level tailoring. I'm currently approaching 300 tailoring. The best grinding spots I've found so far are:
Deadmines: Linen. A no-brainer. Just pull the whole instance and hit them with downranked AOE spells to conserve mana.
Stockades: Wool. Another obvious choice. Many of the mobs here can knock you down or interrupt your casts, but that shouldn't be a huge issue.
Scarlet Monastery Armory: Silk. As a mage, I found the Armory to be much more productive for silk than the Library, due to most of the mobs being melee only, making them easier to gather up for AOE. I believe Armory also has a better drop rate for silk, though I'm not running any stat gathering mods to be certain. At 70 it's possible to pull a couple sections at at time.
Dunemaul Compound, Tanaris: Mageweave. This is simply the easiest area to run laps and rake in mageweave. The drop rate is good and usually nets 2-3 pieces of cloth. Sometimes run into farmers, but they usually leave with a 70 player cleaning the place out quickly. Just be polite and don't kill the named quest NPC in the cave, and if you see your own faction there, ask if they're questing. If it's the other faction. . .well, they're on the wrong side, aren't they? Tanaris is also the closest flight path to your trainer at this level, over in Theramore, so it's easy to go pick up new recipes as you skill up.
Blackrock Stronghold, Burning Steppes: Runecloth. This is a great area for runecloth. It's one of the areas I used to gank farmers on my pvp server once upon a time. With Burning Crusade out, it seems mostly empty on my two servers lately. Not only do you get a nice respawn rate on the mobs inside and outside of the building, but there are three chest spawn points as well: One by each fire outside, and one (really two) inside the inner ring where the elite guy is. Oh, don't bother with the elite, it seems you can't actually kill him, as he's a quest NPC set to "submit" after you beat him down a little.
Any Manaforge, Netherstorm: Netherweave. The lower level guys at Manaforge B'naar provide easy kills and a short trip to town to sell vendor trash. I'm Scryer rep, so I farm these for Sunfury Signets and Arcane Tomes for a nice double dip. The ghosts at the Ruins of Enkaat also have a good drop rate and are somewhat easier kills.
For Felcloth, the satyrs in Azshara are great, but I am certain I can go from runecloth to netherweave without needing to hit Azshara.
