One of the best gifts I've given my wife was not a "thing" at all. It was a pair of concert tickets to the Trans Siberian Orchestra. Gifts like an event or an experience tend to be very special and unforgettable.
^YES. A concert, a dinner, time spent together. That's a great gift.
Old Married Lady's Advice:
Do something she's never done before, but has always wanted to. It doesn't have to be fancy. One of the best dates I had with hubby was when he took me to a tacky little miniature golf place. I had told him that I'd never played miniature golf, but had always wanted to--and he remembered that. We had a great time and laughed ourselves silly. Is there a town nearby she's always wanted to visit? Gift wrap a little suitcase and tell her you're spending a long weekend there---or even just a day-trip. Live near the water? How about a dinner cruise on the water? Is there a tourist spot nearby she's always wanted to visit but just never got around to it? Visit it together and have a good time.
If you are living together, you could get a nice collection of Christmas ornaments for the tree, so that you two can start a new holiday tradition of your own. You can put in a nice, romantic card about how it's for this Christmas and all the other Christmases to come.
Has she ever told you about a childhood toy she always wanted but never had? Get it for her and give her a card, saying she makes you feel like a kid again (assuming you are actually not still a kid, that is).
Really, what makes a gift really special is that the other person put a lot of thought into it, that they really KNOW you, not how much they spent or getting something fancy. It's really about the experience. To know that your special someone has listened to you, knows you---really knows you--and wants to make you happy--is the best gift in the world.
