The San Gorgonio Inn is located in Banning, California.
Variations of this postcard appear to be quite common — I saw five on eBay today. There are several variations in the prices shown on the sign, the wording on the bottom of the sign, and the colors of the sky.
According to an entry in Wikipedia, the original San Gorgonio Inn was built in 1883 and served as a stagecoach stop until 1920 when a fire destroyed most of the guest rooms. The inn flourished with the coming of both U.S. Highway 99 (now known as Ramsey Street) and of Interstate 10. It remained a popular, low-cost coffee shop until 1984 when the owners died. There have been several changes in ownership since then.
The most recent information that I could find on the Internet indicates that the restaurant is closed, but the sign is still there.