Well here is a great example....
i was in a party where we had 1 rouge.. 2 tanks, 3 wizards and 1 cleric and 1 bard, i was a wizard...
Rouges in these parties usually pull (Pull monsters to our exp spot) with crossbows which is pretty good for shooting long distances and also because the mobs run really fast, we tried letting a wizard pull >_< lmao dead after 1 hit. Rouges in a party do extremely well other than the fact they can pull, their daggers have fast damage skills, crossbow as well, higher damage so you can go with either one.. but i do suggest using a crossbow in a party for pulling and then just switching off to daggers when fighting the mob while its being tanked. or even use the crossbow while the mobs being tanked.
Wizards - in parties wizard is pretty much that guy/girl who does higher dmg then anyone else.. but if hit once lol goodnight.. in the same par
ty with that rouge i was talking about up top. the wizards just stand together and spam out spells which of course is great and doesn't affect the party exp in any way just makes it go faster.. Wizard is awsome if you want to do amazingly high dmg over short period of time, but low defense... still a great job to be.. both are awsome. and great additions to any party..
both jobs can really be used in any occasions.. Rouge is scary at times...they can transform into the monster they just killed (or party just killed) and fight as the monster lol... after seeing a lvl 70 Rouge dressed up as a Dark Kara (sry if misspelled) in hotan... i just was amazed..
also the rouge can (in cities) transform and steal ppl's costume (everything the person is wearing the rouge will get) but still have to ask a few more questions.. didn't understand the whole costume stealing thing lol. also rouge turns invis ^_^ and tracking is awsome.
wizard of course is awsome too

i saw 4 of them all dressed up as theif lmao... very scary to traders doing 2*+.... they would all stand together and at the same time all cast freeze / fire / lightning / earth... was sooo crazy lol!! loved it
both jobs are awsome.. just see what your playing style is... more melee ... or more magic

ohhhh tell me about clerics and bards cuz everyone i know is a pussy and is too manly to be one, so im being nice and being a cleric for them.