High End Ranger PLing - What zones?

[qualia]

PLing my ranger bud, he's level 21. Currently using a 60 druid with robe of the spring, manastone, etc to PL. Assuming a druid would be the best means to PL at this lvl range (also have a geared 60 monk and just about any other class). What zones are the best option for this level and what zones will be good for future levels?
Been so long since I've played I can't remember all the options anymore.

Thanks