Simply replace the unfilled areas such as "[]" and "[date]" with your information.
Dear [Customer],
Thank you so much for allowing us to serve you during your [luncheon/conference]. We recognize that you had many options when selecting a location to host your event. We are thankful that you chose [location] and look forward to the opportunity to work with you again. We offer a variety of services and should be able to meet your needs for any occasion.
We hope that you enjoyed your experience and that our service and [cuisine/selections] left you completely satisfied. We appreciate any comments and suggestions you may to improve our quality of service.
Thank you again for choosing [location name]. Please let us know if we can ever be of service again.