Elizabeth Mayhew did a really lovely segment on the Today show a couple of years ago on the importance of writing handwritten thank you notes for gifts and hospitality you receive over the holidays. The segment and accompanying article, which gives great tips for writing a meaningful note, is available at Msnbc.com and is still highly relevant for today's times. I encourage you to check it out!
You can use personalized cards for holiday thank you notes or you can select a seasonal design for a more festive look. Here are two of my personal favorites from Cid Pear, available at FineStationery.com: