Some options I could see being viable are things like helping the Guildmasters of each of the crafting and gathering guilds get things done that don't pertain to their particular Guild members, or would help their guild members but can't be done as a crafter/gatherer.

For instance>

Code:
At level Thirty, Sisipu offers any DoW/M a quest to help her route out a vicious monster that has been indiscriminately attacking the members of her guild when they are fishing along the coast. Through the process of a few cutscenes and micro instances you follow her around the areas outside Limsa. She proceeds to start fishing while telling you stories about what happened during and right after the Calamity. Telling you more about how the fishing guild helped in clean up and repair of their fair city. 

The first few micro instances end when you kill small pugil's she fishes up that are between level 20-25. But she claims these are not the pugil's she's looking for. 

The last micro instance she pulls up a giant version of a Pugil with a unique name and appearance. It attacks her knocking her down and you step in to fight it. When you defeat it she takes it back to the fisher guild. 
On arrival in the fishers guild to turn in the quest she offers you a choice of different weapons that she claims she found inside the fish when they were prepping it for the Culinary guild and you get your choice of different unique weapons.
Things like this would be entertaining and add more life to the main cities letting you fall in love with characters you might know but not really have had a huge chance to do things with. They would also give players a chance to get unique weapons and armor from non-dungeon areas.