Dear Fris,
I am writing this letter to thank you for you warm hospitality accorded to me during my recent visit to Beijing.
I would also like to thank you for your interesting discussion with me which I have found very informative and useful.
During the entire visit, I was overwhelmed by the enthusiasm expressed by you.
I sincerely hope we could have more exchanges.
I am looking forward to your early visit to my hometown when I will be able to pay back some of the hospitality I received during my memorable stay in beautiful Beijing. With kind personal regards.
Faithfully yours.