Dear _____ and _______ (通常是夫妇俩的名字）,
It was great to see you on Saturday.It was so thoughtful and generous of you to invite us to dinner.Both of you are truly impressive cooks!
It was so nice to see you and catch up.We always enjoy spending time with you all and we're looking forward to next time at our place!
（注：we're looking forward to next time at our place 已经表示想回请的意愿及期待朋友光临的心情）
Thank you again for your hospitality.
Warm Regards,
__________(请签上大名呵呵）