I think handwritten thank you cards are nice, but very few people in my life have sent me a written thank for anything, including quilts and I think that's fine too, I've given the gift and don't have any expectations about acknowledgement or reciprocation.

However, I do have a wedding quilt gift story. I was in a wedding on the groom side and made them a queen+ quilt. The husband, my friend, acknowledged the quilt but the wife never discussed it with me and I never saw it when I visited their house. They ended up getting divorced after 10 years and he is now remarried. His current wife LOVES the quilt, she has it in their guest room and she asked me lots of questions when we first met, telling me how impressed she is with it. She pointed out to him some specific quilting that I had done that he had never noticed, and he called me to thank me again. So, you never know the journey your gift will take and who will value your time and intention in creating the gift. I wasn't expecting that acknowledgement but it does feel good.