I have played WoW, I might start back up this summer. Every class has something special about them. Mages have crowd control, good magic damage, and are living vending machines, as you can create infinte free food and water to heal HP and MP (outside of battle)
Ice is more defensive, Fire is more aggressive, and Arcane mages are only good at high levels and they are basically glass cannons. You can level either as fire or ice, ice though you need to target more than one monster at a time with your aoes. You can use all spells; your talents starting at level ten make your fire/ice/arcane spells more powerful. Mages have low def and Hp but high magic.
There are other caster classes you may want to try. Shamans can summon totems to aid them in battle, and wear armor so they have higher defense, and use hammers so they have higher melee attack, and can heal themselves in battle and have good burst spells. The downside is they have no crowd control and limited mana, and their healing/melee/magic is worse than that of priest/warrior/mage.
Warlocks are quite powerful. They have good offensive magic, and good debuffs/drains against enemies, and can summon demons to help them in battle. Their weakness is that alot of their moves require special soul stones that they need to make
Priests are primarily healing, but they can also attack. Shadow priests are basically warlocks with about equal drains, but no summons, but can switch out of shadow form and heal. Priests also have a buff tree and a healing tree.
I play as druids, and they can basically do everything. Moonkins have high HP and Def, and can use a variety of spells, but really only 1 or 2 spells of each type (dot, cc ect) and have low MP, which can be remeided in a PVP match due to inervate. They can also shapeshift into cat (rouge clone) bear (warrior clone) tree (priest clone) dolphin (water travel) cheetah (land travel) and bird (air travel) They arn;t that great honestly, but if you master using all their forms toghether in battle, they can be excellent if you have good gear. Plus you only need one character to play every class :)
Hope that helped!
edit- hunters are also ranged. They attack with bows and can lay staps and sting enemies. I found them unfun, but alot of people really like them, and they are a powerful ranged class.
Also, play as much WoW as you want this summer, but be careful once school starts. WoW is a great way to fail becuase you won't want to do your homework. If you have a job you are fine becuase most jobs you go to work all day then have 2 hours of free time and play WoW then :D