I'd recommend "Streets of Silver" by Living Imagination. this is a hefty tome for a port city in which the whole city is mapped out and locations are given in great detail. it is set in their "default" setting, but I plopped it down into my campaign world with no fus whatsoever.
It not only contains detailed maps of all of the neighborhoods and shopes (quite a feat considering the size of the table) but aventure hooks galore. It also includes local customs, laws, important people - did I manttion is is a heft tome? Probably the most complete city supplement I have ever seen.
Otherwise, if you don't mind converting - Marienburg for the last version of WHFRPG - is filled with some great ideas, and makes for an interesting city. Details a few places in the city well, but leaves you room to expand. i plopped this city into my world too.
Hope this helps.
Razuur