英借文辞典 「お」⇒「お礼--歓待に」
        「お」⇒
「おもてなし」
          
「か」
⇒「歓待」

            「か」⇒「感謝--歓待に」
        「も」⇒「もてなしに感謝」

状況に応じて借文しましょう。
状況 歓待に対する感謝・お礼 (下線部分の代りにカッコ内もOK)
歓待してくれた人に非常に感謝して I would sincerely like to thank you for your kind hospitality extended to me on Saturday.

I would like to thank you most sincerely for
the welcome you gave me during my recent visit to your firm.

Thank you very much (My sincerest thanks) for
the warm reception shown to us during our visit to your factory. 

We all want to extend our appreciation for such a wonderful afternoon in Narita for the lovely lunch and
all of your generosity. (成田空港で楽しい昼食を歓待されて)
簡単なお礼 This is a brief thank you for Gerry Brown and myself for your kind hospitality during our stay in Kobe for the exhibition last week.

This is a quick note to thank you for the opportunity to play golf with you last week at Ebina Country Club.

Just a small thank you for
your hospitality in Japan.
遅れてお礼状を出すとき
May I express my belated thanks to you and your colleagues for making me so welcome during our brief visit to your factory. We were particularly grateful for your hospitality during our stay in Japan.

Though belated, please accept my thanks for
inviting me to your press release last month. I was much impressed with your newly developed products.

Just a small belated thank you for
your hospitality in Japan.
出張先・旅先での歓待にお礼 I wish to thank you for all the nice things you did for me during my stay in Los Angeles. Your hospitality made my trip enjoyable.

Thank you very much (My sincerest thanks) for
the warm reception shown to us during our visit to your factory. (下線部分の代りにカッコ内もOK)

This is a brief thank you for Gerry Brown and myself for
your kind hospitality during our stay in Kobe for the exhibition last week.

May I express my appreciation to you and your staff for
making me so welcome during our brief visit to your factory. We were particularly grateful for your hospitality during our stay in Japan.

I am writing to thank you for
all of your attention and your hospitality during my recent visit to Japan. Your staff tried every effort to make me feel comfortable and definitely succeeded in making me feel very welcome.
  
貴社のスタッフがよくしてくれたことにもお礼

I would like to thank you most sincerely for
the welcome you gave me during my recent visit to ----, and for the opportunity you made possible for me to meet, and hold discussions with, your senior management in your department.
  
歓待へのお礼と共に貴社の役員にも会えてお話しが出来たことにもお礼

Again, I thank you for your hospitality. It was so nice to see you again. I hope to visit you again in the future.
  さらっとお礼を言って、再会を希望する。
部下の出張先での歓待にお礼 Thank you for hosting our Engineering Management Team in October. It was a pleasure to have our management teams get together and discuss how we can better prepare for the challenges ahead.
打合せ・会合に招かれ、歓待へのお礼
I wish to express my sincere thanks to you for giving me the opportunity to attend your ---- meeting last week. I was very grateful for your warm hospitality extended to me during my stay in -----.

Your hospitality was greatly appreciated and we sincerely hope that ----
食事・パーテイへのお礼 We all want to extend our appreciation for such a wonderful afternoon in Narita for the lovely lunch and all of your generosity.  
成田空港で楽しい昼食を歓待されて

It was very kind of you to extend such a warm invitation to us. We enjoyed a very pleasant and friendly dinner (party) that evening.

I would like to thank you most sincerely for the wonderful (splendid, superb) dinner (luncheon) at the ----- restaurant on May 1.
(下線部分の代りにカッコ内もOK)