Whataburger seems to have made a very good and lasting impression on you....I'm sure that the company would love to hear from you just as they did from the Lowders. If you write them a nice story telling of your favorable experiences they may even add it to their website. Here's the submission page:
Down toward the bottom, there's even an option to send a copy of your letter to the Chairman as well as the President (I'm assuming it's the President of Whataburger, not the President of the United States)