To write a good wedding thank-you note, mention the gift and how you plan to use it or how you have already used it. Mention how you look forward to seeing the guest at the wedding, or mention a specific interaction you had with the guest at the wedding.
Make thank-you notes as personal and detailed as possible to show your guests you appreciate the time, effort and money they put into your gifts and into coming to your wedding. Send thank-you notes as soon as you can after receiving the gift, even if that means sending them before the wedding.
If a guest gives you a gift that you plan on returning or that you never plan on using, do not lie, but choose to focus on something positive rather than mentioning that you do not like the gift. For instance, if the gift that you hate happens to be in your favorite color, mention how much you like the color and how thoughtful the person is for remembering your favorite color. If some guests do not get you a gift, consider still thanking them for spending the time and money to travel to your wedding and celebrate with you.