Dear Sir/Madam
I am writing this to express my thanks to you for the opportunity to visit you and to meet the members of your staff. It was a pleasant experience to be able to take a closer look at (name of organization) and hear of the many ventures being undertaken.
I was most impressed with your organization, especially in the area of quality control. I am grateful to you for the interview and will eagerly look forward to hearing from you.
Sincerely,