your options are larger than just fates,

there are of course the fates which will act as a main stepping stone as you hunt around.

The hunting log provides large bonuses and each class has it's own unique log.

Guildleves are repeatable on alotment, and you can gain bonus exp for completing them on higher difficulties.

Guildhests can be undertaken by parties, these are a mix of a guildleve and a fate, and do not take alotment.

When your new class achieves the required levels you can begin doing dungeon runs with them to earn gear and large exp rewards on completion.

not to mention that each city has it's own pool of sidequests from 1-50 to pull from, so as long as you don't complete them all with a single class and waste them, you've got plenty of content to keep you... well... content.