You don't see all that much of it, but I like the style of the "utopian" colony of Miranda in Serenity.

I'd troll through the city-planning/urban design/architecture blogs on line, as there are usually pretty high-concept images there.

Or do a quick google image search for City of the Future, lots of people drawing there ideas. These days the trend is tons of green space, smooth curves, and car-free transportation. Earlier eras favored huge, "efficient" highways and rows of identical super towers spread across vast vacant parks. Extremely tall and/or self-contained buildings seem to be a common feature in one form or another, as do agressively humble rural or psuedo-rural enviornments. Burying transit under ground is an idea that won't go away, as is the idea of airborne transportation landing on skyscrapers, be they zepplins, helicopters, or flying cars.

I like this 1925 Popular Science cover:



They actually didn't do too bad, as these things go. Many/most big cities (at least in the US) do have underground electric railways (some have them elevated or at street level) and we do indeed vertically seperate fast car traffic (on highways) from slow (on surface streets). Modern buildings also frequently have the basement garage and garden areas on roofs and terraces they predicted.