Friends,
I like to think it much depends on what you wish to DO in / with the city. IMHO, most 'NWN cities' I've seen are tiny, built with vignettes; only building a few shops, taverns, guildhalls and 'pretending there is more you just cannot go there'. This is OK, if the goal is to provide essential provisioning, rest and little else. On the other hand _if_ your PC is a bard, rogue or assassin or other 'urbanophile' - such small places afford nowhere to hide (the rogue that goes 'underground' in such places may be unpleasantly surprised to find a single party can cover a city searching for a rogue there is no realism there). Yes, a big city is a LOAD of work - I'm _still_ building out a large city in our server - presently it is comprised of outdoor 16x16 areas 35 if you count the city walls, totaling 20 Areas within the city walls. There are about 10 inns in the city, and about 50 merchants. Public transit in the form of a 'magic carpet' depot makes getting around the city easy cheap and fast, and the city is a nexus of ship and wagon-borne travel too. There are about 15 easy to access sewer Areas, and about 100 total sewer Areas in total. A wily rogue could travel from one end of the city to the other by any of several routes NOT on the surface, if willing to hazard the risks. There are numerous defensive structures around the city, many guard barracks and even supply/transit tunnels that are 'secret' for the guard use. It is still a work-in-progress; we are still rolling out features like usable windows and a new merchant system, but the size, large as it is, can be a great boon to a server. Our DMs have a huge range of options when they want to set some event or other 'in the city', and a well-established theives guild (whose HQ includes an 80 Area training maze) makes the place RIPE for all sorts of intrigues. The city features a crafting college, arena, palace, and even some hidden undead. The city even has an extensive crypts (about 25 Areas).
Basically, what I'd like to communicate here is, there is no such thing as 'too big' - we run lag free, crash free with 1337+ areas in the module too. Big is good as long as you are willing to make the spaces you build worthwhile. As a general rule, I try to have at least two purposes for any given Area, but I do make some exceptions in that we need some spaces that are generic households (not every house needs to have a questgiving NPC ready to award hundreds of gold to needy PCs). That said, even some of the peasant homes have some treasure hidden (a few concealed coins or a lost very minor magic), but sometimes the most important thing about a place is what can be spied upon from the windows, balconies or gardens.
Now, the city I describe above is the 'main city' built in a contiguous fashion where all the Areas meet edge-to-edge. Other cities in the server are built in a more typical vignette style and are much abbreviated 'cities' set in far locations - in such places all that is needed was a few patron/questgivers, a couple taverns/inns and a few commoner houses, with hints of an overall city layout and 'more beyond'. The 'main city' for the server was intended to provide a serious location for rogue activities, the rest, are much more peripheral to the server and the campaigns run by our DMs.
I like to give the DMs "room to move". I encourage larger cities in all modules, more Areas make the place seem real, too few make the suspension of disbelieve harder than it needs to be. Largeness is central to the idea of a city, variety within that largeness can help make an urban landscape come to life.
Be well. Game on.
GM_ODA
96.31.77.127