A nice holiday gift for someone might be an in-office whitening at your dentist. Zoom and other in-office systems tend to work much better than the over-the-counter items, and you should always have your teeth examined before whitening just to make sure that they will whiten evenly and you don't have some other issue that should be dealt with first.
Almost any dentist would create a gift certificate for you, if they don't already have them, and certainly any 1-800-DENTIST member would do it, so they could go to a dentist near them.
A quick word about gift certificates. One of the worst ripoffs, in my mind, in the gift certificate business is the American Express gift cards that you buy in the supermarket and other places. First, you pay a premium on them, second, they expire, (which they shouldn't even be allowed to do--it's money!) and third, they charge a service fee every month of approximately 2%!!! So if you bought a $100 gift card and the person you gave it to waited a year, it would only be worth $74. And shortly after that, it would be worth $0. Nice for Amex, bad for everyone else.
So my advice is, avoid them. Get gift certificates at places that you know will give you the true dollar value that you paid for.
Give somebody a white (Christmas) smile. They'll think of you every time someone compliments them.