Answer: I can't really dictate a whole letter but I can help by giving some useful points. Then, u can make sentences out of them!
Explanation: First of all, make a the first paragraph by greeting the person.
Then in the second paragraph, tell them how you got or how u were invited in a party/visit/trip (u wouldn't be invited to a visit. You must have planned it. You can adjust).
In the third one, mention the things that u found weird or unusual.
For a party: No alcohol, wasn't a typical booze booze party, and anything that u found weird(I have never been to a party).
For a visit: U can add how weird you found your host's behaviour and anything u found spooky in their house or anything.
For a trip: u can add anything spooky or something interesting yet weird
After that, make several paragraphs about the trip/ party/ visit.
And in the last, tell them u feel about the event and pay ur regards.
