That's it to my thinking---not that I ever feel like I'm ever getting the full "bang" out of my captial city. A night out just gets you tangled up with the city denizens in a slightly amplified way because the rats come out of their holes at night.
The real trick is getting the city activities (subplots) clearly laid out so the DM can access them for adventure/carousing fodder. Then, if you need a random element, you roll on a customized table as to who/what they bump into.
Seriously, I'd love to see how Gygax ran Greyhawk City (or Melan does his City of Vultures). My original group generally hand-waived city activities (unless it was an in-dungeon city---which were special). That means I've been "winging it" without a blueprint for my home campaign.
Forgive me if I am speaking past the topic (I am honestly not sure if I understand what y'all are looking for/doing).
What I have done (labor intensive) is:
a) reduced the size of the Capital City by a factor of 10 (i.e. 2000-3000 inhabitants)
b) mapped all the building exteriors
c) mini-keyed a large number of the major shops trying to add an NPC name and some flavor (a la CSIO)
d) interior mapped & keyed some of the major locals/action-points, e.g. church, palace, main inns, jailhouse, witch's cottage, wizard's guild, military academy, gate houses, etc. (...and yes Byrce, parts of the darn sewers!)
e) written a few historical notes and city/campaign-wide plots, and listed who's in which faction/sub-group by mapping out a chain-of-command (whom reports to whom)
In the process of doing all that, the NPC's and their various motives started to emerge. That way, I at least have a cast of "extras" I can throw that the party when I think it fits the situation.
(...of course, all this is "half baked" and needs more time and work than I generally have available.)
In truth, where I fall down, is that I DON'T generally throw much at the party because when they get into the city they literally "go to town" --- visiting all sort of people/places they already know and making little plans. Sometimes they (and I honestly just don't get this---Generation Gap?) GO SOMEPLACE JUST TO TELL AN NPC WHAT THEY'VE BEEN UP TO SEE HOW THEY REACT TO THE NEWS?!?!
So basically, they are so active in-city, I become very re-active as a DM. My dissatisfaction with my DM skills in that case---similar to my issues when they were in the Palace---is that I don't feel that they get a sense of the hustle-and-bustle of a populated area.
Also, the organization of all the city-mess is flat, i.e. there's a lot of info there but it's not indexed really, except in my head (since I created it). The map provide structure...but after that...ugh!
Again: Anyone who feels like they've "nailed" running city adventures, I'd love to hear their methods---just so long as it's not "improv heavy" as to me that's really a non-system and not much help.
Am I even on topic?
EDIT: Maybe the tables looks like this:
TABLE 1 - What are you doing? ---> roll on appropriate subtable(s), maybe even combine two random results
SUBTABLES - Who/what you might bump into and the page # of where to find more info.
Sort of a situationally appropriate set of Wandering Monster (sub)tables.