It's been a while since I've done a proper dungeon guide video, so here you go. Lost City of the Tol'vir is a level 84-85 dungeon for 5 players. It is located in Uldum near the bottom centre of the zone. There are 3 bosses (General Husam, High Prophet Barim, and Siamat) and an optional fourth (Lockmaw). On Heroic difficulty there is another boss (Augh) that joins the encounter with the optional boss Lockmaw. This instance is easily soloed by a level 90 character (I haven't tried Heroic difficulty yet).
My brother is levelling another alt and has been doing some old dungeons and I've been joining in on occasion. This is our run of The Frozen Halls in Icecrown. We ran The Forge of Souls, The Pit of Saron, and The Halls of Reflection back to back. It's amazing how quickly and easily you can complete these dungeons when you're level 86-87. You should be able to solo all of these at 85.
Here is part 2. I'm debating whether to increase the playback speed in these levelling videos to 200% or to just leave it at normal speed. I'm just worried it's going to take a long time to edit and release the entire levelling series. We'll see.
I started levelling two Pandaren Monks and decided to record the whole thing. The plan is to record every moment of their levelling and release it for you to watch. It's going to take a while.