The sentiment in this one is applaudable, human and genuine; but is the syntax excusable?

Full-stops (or periods for our American friends) often do not appear on signage unless perhaps where an abbreviation is used.

In my mind even a comma after Fairmont wouldn't make it right, as the sign is expressing two different thoughts and therefore two different sentences.

My suggestion would be:

"Thank you for staying at the Fairmont. We realise you had a choice."