So, this is the message we were invited to write privately on Airbnb to our hosts. I don't think it should be anything different from what we would say publicly, and this is it...
"Thank you so much for your hospitality and letting us stay, and discover, the delights of your place, the area, and the use of your bikes. They were tip-top.
Your house is so wonderfully located, and the actual accommodation is top-notch.
We hope to see you again."