If you have two White Mages in your party that knows when to rest for MP and when to heal, chances are, one of the White Mage will have full MP by the time a battle is over. Keep in mind that it is not a good idea to have more aion kinah than three White Mages in a party of six because chances are you will not have enough fire power to kill the monster off in a reasonably quick manner. When that happens, the White Mages might actually have to spend more MP healing party members because of the unnecessarily long battle. Support jobs such as Bards are very popular because they can sing songs that will regenerate HP and MP while your party rest.
From 50-60 You will be visiting Maraudon, Sunken Temple, Black Rock Depths and maybe as ou get to the upper scale, LBRS. You are unlikely to get a group for Strat, Scholo or UBRS before level 60 unless you have a nice guild that will take you. Theres enough good loot to justify a few trips to all of the dungeons listed. The experience is good but as always, secondary to grinding.