It's going to be awhile before I actually run a game but the setting I'll use will be Los Angeles 15-20 years from now. I live in San Diego, been to LA enough times to have a "feel" for the city. I'll pick up an LA Thomas Bros. street guide (thats a big book of street maps), a little research on the web will round it out.
A few basic concepts:
San Francisco was nuked by a terrorist bomb on a cargo ship, all of the shipping and banking formerely done there has shifted to LA.
"The Big One" will have hit a few years before the game, areas like South Central, Compton, and Watts will be under the firm control of gangs that took over in the lawless period that ensued after the quake.
The classic cyberpunk love for the media thrives, and Hollywood is bigger than ever.
San Diego will have a bunch of exclusive, some walled communities. The cybernetics/biotech industry will be big there. America's Finest City will have one of the highest concentrations of wealth in North America. The way our housing costs are rising this isn't entirely unrealistic.
:x
The only adventure idea I've come up with concerns a corporate defector who needs to be put on a plane to...wherever .Opposition will be a rival corps. security and once the airport is reached the TSA (Transportation Security Agency) will have to be dealt with.
And I guess it would have been easier to say "I'm building my own setting".

Killing some time before th little woman comes home so I can go blow my paycheck for Valantines Day.