I found this gorgeous photo on Etsy, and it’s just too space-tacular to not be Googie, so I’m posting it. (Unfortunately the photographer doesn’t list anything about where the sign is located.)
Edit, April 28, 2010: Thanks to Mike in the comments for letting me know where this sign is located!
This sign is located on State highway 51 between Coweta and Broken Arrow Oklahoma. You can see it on google maps but not too well at this address- 25212 Oklahoma 51, Coweta, OK, United States