[ild]

If you want affordable, build dense, urban cities; not NY style rows after rows of 2 story building, separated by roads, but USSR style large 4-6-9 story blocks, build from concrete (longevity, privacy) with no eventually moldy drywalls, closed for through traffic, with parking garages, public places, playgrounds etc. American university campuses can be good models for residential neighborhoods.

[clock_tower]

Buildings which are just residential (and, for that matter, ones which are just commercial) still tend to produce dead zones, with little to no street life; and it's street life (and walkability) that makes a city, at least if you ask me.

I'd say that the best kind of city -- or district/neighborhood, more accurately, since cities tend to be a patchwork -- is an area of multi-storey buildings with businesses on the ground floor and apartments above them. My understanding is that this is the usual pattern in the Old World; in the US, the North End and Allston-Brighton in Boston, Seattle's Chinatown, and of course Vancouver are among the examples. This isn't a common pattern in the US; I know that parts of NYC fit it (although I don't know that city particularly well), but I've heard that even Manhattan Island is all office buildings, and becomes a wasteland after dark.

I certainly agree, though, that 4-9 storeys is a pretty good height. Smaller than that and you don't get enough density to support interesting streetscapes; larger, and you get wind tunnels and the need for more parking. Of course, sometimes geography (San Francisco, Tehran, most of Japan) or politics (Singapore) force a denser population, and require a more built-up area...

[ild]

USSR has always had ground floor shopping on the street facing residential buildings, also major bus stops have convenience stores attached.

[clock_tower]

It sounds like I should visit Russia, then! Whatever else can be said about them, it sounds like the Soviets really knew how to build a city.