If you're planning on upgrading the account to Legion and gearing up your DK at 110, just do world quests (including world boss every week). You'll get gear that more than enough to farm herbs/ore in all zones very quickly.
If you're using the default questing pack, you might run into the problems I've run into lately when using the Cataclysm profiles. The auto loader seems to keep trying to make my toon go back to Hyjal by using the death gate and then flying north until it bumps into the Ghostlands barrier. I think at level 83, I had to manually load the Uldum profile. The Uldum profile crapped out at like five bars from level 85, so I manually loaded the Twilight Highlands profile so that it'd finish off leveling to 85. Beyond 85, though, I didn't run into any problems with the questing packs.