WPL: Random quests near Sorrow Hill, and Cauldron quests are really quick and good for xp - so a good alternative.

EPL: quite a few of them are collection quests, so not really interesting, except for these 5:

http://www.wowhead.com/?quest=9136 Savage Flora

http://www.wowhead.com/?quest=9127 Bone Fragments

http://www.wowhead.com/?quest=9132 Dark Iron Scraps

http://www.wowhead.com/?quest=9125 Crypt Fiend Parts

http://www.wowhead.com/?quest=9128 Core of Elements

start stockpiling 150 of each of these 5 materials needed (if 5boxing ofc) from AH or otherwise, and when you hit lvl 55, go collect a whopping 28650xp pr quest, giving you 143250 xp totally. It takes 148200 xp to go from 55-56.

Any gold spent, is easily re-earned when you start dailies @ 70 anyways.