Somewhere mid lvl 84's while doing the quests in Uldum with Harrison Jones and Bronzebeard completed almost every quests in the zone I could find and searched around to find but was out of quests. Somewhere I was missing a quest or completing it. The way quests are linear each unlocking others that can easily happen. Only had two dungeon quests left for the zone that had picked up so figured it was on of them yet to be complete preventing access to more quests probably. Couldn't figure out how to get to Twilight Highlands at the time and had not picked up the quest in Ogrimmar as yet to start the chain to get to the zone either.
Only Cataclysm dungeon hadn't yet found and unlocked was Grim Bitol in Twilight Highlands. And had two dungeon quests for two different dungeons in Uldum zone. Mid way to lvl 84 and out of quests decided to finally queue up from running quests to run my first set of Cataclysm dungeons just doing randoms. Didn't feel much like tanking for my first step back into dungeons so queued up as dps and ran several dungeons as dps till close to lvl 85 and by that time was just too tired. Seeing the new dungeons for the first time was all interesting. Had completed Halls of Origination quest for Bronzebeard in Uldum and still couldn't find any more zone quests unlocked anywhere in zone. Called it a night there.
Back in game again later after a marathon sleep found the starter quest which starts the chain which gets you to Twilight Highlands right there in Orgrimmar in front of the Warchief's building. So eventually completed the initial chain quests which got me to the Twilight Highlands and much different zone to being in the desert zone of Uldum. Wasn't but a few quests after being there at the port that hit lvl 85. Hard to believe the leveling experience is now over after it just started.
After which just went exploring the zone a bit to see what was there in the Twilight Highlands.