Thank you for one of the most memorable days of my trip.
为了旅途中最值得纪念的一天，谨向您表示感谢。
Thank you for one of the most enjoyable visits we have had in many months/ for some time.
在您处的'参观访问，是我们几个月（一段时间）中最愉快的一天。谨向您表示感谢。
Thank you for doing so much to make my trip to New York interesting/ pleasant / fruitful.
为了使我去纽约的旅游有趣（愉快）（大有收获），您做了许多事，特此致谢。
Thank you so much for your generous hospitality.
非常感谢您慷慨的款待。
I hope something will bring you to New York soon， so that I can return/ reciprocate your kindness/ hospitality.
希望不久您能有机会到纽约来，使我能答谢您的盛情款待。
You must give me an opportunity to return your kindness when you visit my home.
希望您光临我处，使我能答谢您的盛情。
Thank you very much indeed / ever so much/ so much.
最真诚地（确实）（非常）感谢您。
Many thanks for your kind/ warm letter.
