It's a relatively easy location to identify from Julius Shulman today. This is "Job 139: John Kewell, Airline Buildings, 1947"
Here's a closer view of the entrance.
You can see the Western Air Lines building on the far right of this picture of the United Air Lines building. Note that I'm writing "Air Lines" as two words in each case to reflect the signage.
All from Getty Research Institute
Western Air Lines was at 6060 Avion Drive and United Air Lines was at 6020 Avion Drive. The view below on the left is from 1952. The light well at the southern end of the Western Air Lines building was filled in sometime between 1963 and 1972. The front survived until at least 1994, but has since been replaced with a new building set further back from the road (the rear appears to be unchanged apart from a few additions).
Historic Aerials/Google Maps
Avion Drive has been re-aligned over the years, so the Googlemobile doesn't get that close to the United Air Lines building, which is a shame because that building is still standing.
As a reminder, I posted this picture of the northern end of the Western Air Lines building just over a year ago. The full post is here
Originally Posted by HossC
The last photo looks across W Century Boulevard. I'm guessing that this was taken from the McCulloch Motor Co.
Getty Research Institute