I know it's way to late to do this now, but if you remember, you might consider doing this next year, or for her birthday or both. The last thing I mention in this response you could possibly do tho.
What I've done for the past 3 years is I've gone with something from the Bradford Exchange as the "big surprise gift" she has no idea about and I refuse to even give her a hint, and if it isn't heavy, when I wrap it, I make sure to put it in a box that I can make heavy so she really and truly has no clue what it might be. With the ring I gave her 2 years ago, (see picture) I wrapped the box it came in, then put it in a bigger box, wrapped it, then put that into yet another bigger box, then filled that box with some of her books from her bookshelf, that eventually she was looking for but I had no idea what books she was talking about until she opened it Christmas Day lol, as well as 6 or 8 cans of baked beans, which she won't eat. SO when she first opened it, she thought I had gotten her her own books, and baked beans. She was NOT impressed. Then she saw the other wrapped box, opened it, swore at me because there was yet another, and when she opened that last box and found the ring, the waterworks coming on was immediate.
Oh I forgot to mention, my mother taught me the joys of using LOTS of tape on super important gifts.
So here's what I got her this year, last year and the year before.
Last year I got her this. Obviously the engraving is not what this picture says, I had it personalized specific to my wife and I. The center piece spins.
The year before I got her this. Again, obviously the engraving is specific to my wife and I.
and this year I got her something very similar to this but it was a promotion specifically for Christmas for a husband to give to his wife so the engraving on the heart on the stem of the rose instead of saying "grand daughter" as it does in this picture is engraved with both my wife's name as well as my own.
Additionally, I printed off a copy of a poem titled, "One Red Rose" that was written by my grandmother before I was born (so it's over 50 years old) that holds a very special place in the hearts of everyone in my family, so much so that it is read at weddings, funerals, and many in the family, including me have used the poem to propose to their now wife or fiance as the case may be. There are 3 copies of my grandmothers book of poetry. I have one, given to me by my mother, two of my uncles, her older brothers have the other two and they will be passed down to other members of the family as and when required and appropriate so these works although we can share them, remain in the family.
In 2016, while yes I got her a bunch of other stuff, the big surprise was a poem I sat and wrote to her that answered that question she loved to ask me and had been asking me for years, ALL THE TIME.....and still asks to this day, "how much do you love me and why?" I gave her those answers in that poem using the experiences we've had together from the day we met, to the day we became a couple, and everything in between and since.
After I wrote it, I sent a copy to her older sister to get her opinion. She told me it would make her cry, (it did) I had it framed before I wrapped it, and it hangs on our wall to this day and beginning with that poem 4 years ago, it's become a bit of an unintentional tradition that when she opens THAT gift that I won't even give her a hint what it might be, it's made her cry. She knows THAT gift this year is wrapped and under the tree and has been since the middle of November shortly after I put all the decorations up inside and out and while I know it's driving her nuts, she's not asking me if she can shake it this year like she has in other years.