Oh and don't forget, anytime you are herbing - invest in some Darkmoon Firewater to double your gathering speed, and Demonsteel Stirrups to be able to pick herbs while mounted. (Or use that annoy ugly Shredder mount. If you chose this path do yourself a favor and download an addon the mutes the sound effects
)
If your going for a long run you might want to consider Leystone Hoofplates to keep you slightly faster than the competition (doesn't stack with Death Knight/Paladin bonus, or pathfinder.)
And Stonehide Leather Barding will stop you getting dazed which should give you another edge, or at least make farming slightly less annoying (If you are in a tank spec you won't get dazed at all so this isn't required).
Some of these items can get pretty expensive but herbalism is in a state right now where you'll earn the Gold back within the first 15mins.