Dear…
Please allow me to extend my gratitude to you for allowing me to be present the __(type of award/etc.)__ at the __(Name of Event)__. __(Name of cause)__ is something I __(strongly support/feel very close to/etc.)__ and I was thrilled to be there. I can’t tell you how special it was for me to see the __(type of ceremony)__.
The event was done extremely well. The __(highlight of event: example: ceremonial tribute)__ was exceedingly impressive. It was such a memorable event and will be an experience I never forget.
Thank you again, __(Name)__, for allowing me to be present such an unforgettable event. I greatly appreciate that kind gesture from you.
Sincerely,