What I did, as 3x horde RAF linked accounts and a 70 protection paladin to boost:

Levels 1-10: Quested, was level 10 before I was finished with level 6 quests.
10-20: SFK, at level 18 got the three SFK quests and completed those, turned them in just in time to ding 20.
20-43: SM Armory and Cathedral, got and completed the SM quest at level 30 and turned it in at 43.
43-51: Zul'Farrak, turned in quests at 51 to get a bit into 52.
52: BRD pre-req quests (gathering elemental stuff near Flame Crest, killing Overmaster Pyron, the first "Kill on Sight" quest, Commander Gorshak and follow-ups that lead to assignment to kill the Emp" - This was enough to get to 55.
55 (needed 55 for the Molten Core attunement quest): A full BRD clear, completing all quests. This got me to 58.
58: The easier Stratholme quests (Archivist, Plagued Flesh, Scourge Data, Fras Siabi). This got me to nearly 60.
Remaining XP from 59-60: The 30-item turn ins for Marks of Crusade and Marks of Dawn at LHC. I had collected all of these doing BRD and Stratholme.

I had 3 characters being boosted, so nearly always had room for 1 in the group. Dinged 60 in 1 day 7 hrs played - I think I could do better doing it a second time, spent at least a couple of hours setting up my macros and keyclones, as the leveling characters just stood in xp range until Stratholme.

As a little note, one of the characters I was leveling is a warlock. She hadn't done any of her pet quests, except for the imp. I went and did a couple at level 60 and got full XP as if it were a level 60 quest. One should consider that if leveling a team of warlocks with RAF & boosting.