I had a lot of fun with the last two Baron Sablemane quests in Blade's Edge. The next to last the quest chain was "Massacre at Gruul's Lair".
This quest (and all quests level 66-70) I duoed with the same guild Warrior. I was wearing mostly Tier 2.5/Tier2/GM Weaps having only replaced my Neck and Cloak by that time; he was wearing random TBC Blues/Greens and a Zin'Rokh. We were level 66ish at the time, and all the mobs we had to kill for the quest were 67, heavily armored, with 25k hp, and usually came in pairs.
Needless to say, it was pretty tough, but the part that was fun for me was sneaking around the camp. I basically stealth scouted a way to mob, then had to lead the warrior around avoiding patrols he couldn't see. Felt very Thief-ish
Followup to that was "Showdown". What's not to like about this? You knew Sablemane was a Black Dragon, you knew what was going to happen when you called him. Gronn on Dragon action!

Still have the signet that starts that fight.