RIP.
The great thing about these old shows and movies is that if you want to know how the city looked back in the day you have the references to do it.
I bet there have been enough shows and movies set in both L.A. and NYC that you could put a fairly complete montage of changes from the 1920s on. Add in news photos, advertising, crime scene, survey, and personal photos and it would damn well be a complete record of change.
We had a thread about a site that does that with photos but I'm thinking you could mostly do it with film and use photos to fill in the blanks.