A city coveted by many, but owned by none. (concept for review)

[Steel General]

Just to throw out anotehr idea, instead of a small military, you could have a small civilian constabulary (or whatever), and then each of the merchant "factions" could have their own private "security forces". Disputes between factions could be handled in the "boardroom", so to speak, or could spill over into deadly street brawls between the "private armies" of the factions.

[Ascension]

In such a city, it's my thought that the guilds would run the city as a defacto government of merchant princes or maybe left over nobility. In either case various factions have their own agendas and I would think that some sort of walled off sections for the various feuding families/guilds would be present despite lack of immediate exterior threats, sort of like enclaves. Also, despite its distance, a city with that much wealth would be highly coveted and always under a threat...even freemen will protect their homes from marauding tribes. So, I would think that this city would be walled nonetheless, taking into account the evolution of the city. On the other hand, a Great Fair (a la David Eddings) is a town of tents under the control, and policed by, one certain kingdom thus needing no walls. So those are 2 options that I see: walled city with walled enclaves and private armies of feuding factions or a great fair type of tent city already under the rule of a kingdom. To go out on a limb, it could be a thieves den or pirate city with slapdash and shoddy construction and the usual lawlessness, debauchery, and villainy with tunnels under the walls, secret entrances, bribed guards etc. that in reality remove the effectiveness of any security measures. Or lastly, it could be a nomad city...sort of a city on the move, depending on the season, where all of the buildings are actually wagons and they migrate up and down the coast.

My 2 cents

[Aristotle]

some sort of walled off sections for the various feuding families/guilds would be present despite lack of immediate exterior threats, sort of like enclaves.

I'll likely go with walled enclaves for the trade houses. As for the rest of your post: Gold mine! Seriously, cool ideas. If not used here, I'll save them in my notebook for later use.

[Ascension]

Heh heh, you n me both Funny how stream of consciousness brainstorming works. Think I'm gonna do me up one of these ideas.

[Aristotle]

A city like this would become a hub of trade and negotiation between tribes. A great fair of tents would rise outside the city walls, as tribes come and go to trade at the city.

Great idea. The city is already home to the largest market in the world, but a second less official market established just outside might be fun. I'll have to include tent town on the map.

The guilds have been disbanded and free trade reigns, so most anyone can come and try to sell whatever it is they think they can make money on. Of course, space in the main market requires a license. These side-markets might skirt the rules and have no regulations. Shop outside the market at your own peril.

Just to throw out anotehr idea, instead of a small military, you could have a small civilian constabulary (or whatever), and then each of the merchant "factions" could have their own private "security forces". Disputes between factions could be handled in the "boardroom", so to speak, or could spill over into deadly street brawls between the "private armies" of the factions.

Absolutely! The senate runs the city, but mostly just to maintain it and mediate as needed. A police force of baton wielding constables keeps the peace. I considered a division of Inspectors that investigate crimes, but I'm not sure if that might feel too modern. I was toying with using it and D&D 4e to run a CSI style campaign in a fantasy city.

The merchant houses hold most of the real authority, having the influence to gain licenses to maintain large armed forces for the purpose of guarding caravans, warehouses, and so on... I'm definately interested in setting the trade houses up as corporations.