This is what I'm seeing in my run from 55-70.

Dungeon Clear bonus is terrible, and not worth it in and of itself. What IS worth it is the boss and mob XP. So, the best option is to park any raf alts in a safe space, run around with the boosting character and soak up the XP. Zone out, reset and repeat up till you're ready to move on, turn in quests and on to the next place. With regards to boosting characters, I find I really favor Brewmaster for this atm - rez if you need it, can zoom around with Roll/Chi Torpedo and Rushing Jade Wind generally takes care of the masses of targets while I run around.

Honestly, I don't think the XP from the quests is worth it on a time vs reward basis considering the travel time between instances, etc. I'm tending toward a streamlined list of dungeons where my boosted characters can soak the XP with minimal movement, such as Stockades, Hellfire Ramparts, Gundrak, Temple of the Jade Serpent, etc.

The one note of warning I will provide is that it's really easy to hit that instance lockout this way, so it might be advisable to actually spend some time looting along the way or something.