high quality aerials. a bit pricey for my taste, but effective...

You might try Hermosa Beach's planning department, too. They might have some of what you're looking for available to the public.

UCLA Maps room at their central library, not sure what they have in digital form & you'd probably have to go there to find out...

i can't keep this a secret any longer...this is the best site i've found for mid-resolution, large aerial photos of major US cities. there's also GIS info and some other options. really amazing site.

http://seamless.usgs.gov/viewer.htm

there should be several options to the right of the screen...check the '1m ortho' and 'hi-res ortho' boxes as well as the '1m ortho index' box. click 'refresh map' (this may take a few tries), and then scroll until you find LA. zoom in/out, pan until you get what you need, then use the download function (hint: even when it tells you that you can't download the image, you can). it'll come to you as a zipped .tif that you can save.
i just made an image of disney concert hall that is about 8" square.

hope this helps.

terraserver--it's good and free!
http://terraserver.microsoft.com/

also, try the los angeles public library, in person or online.
http://www.lapl.org
you can search through the maps database online as well.
sanborn maps have building footprints on them--although won't be the most up-to date.
a few things: you need a library card to be able to search online. go to databases, then alphabetical index, "s", "sanborn".

this does not probably help you but it's an amazing resource:
http://www.californiacoastline.org/?

forgot to add--
for GIS info, try www.esri.com (data for sale)
they have up-todate building footprints but it's expensive--best to get it through a school.
also, there's a lot of free info around, mostly from the census; also you can do a search on the state of california website--plenty of data available online.