OK....it's always a challenge finding great gifts but here's my advice.
I recommend men read this article first so they know how women think.
As for gifts, women love a night out. Book a restaurant that has some kind of meaning...you know, where you've had a great experience or somewhere that she's been wanting to go to. A great experience is a gift. What's her favourite fragrance, or buy her a massage voucher. These gifts show that you take notice of her and know what makes her tick.
Now, I'm going out on a limb here but I think men are much easier to please. As my doctor once said, just give men food, sex and sleep and they're happy. So I'm assuming that women can pretty much give a man a dodgey gift and provided it comes with a shag, they'll be happy! Ladies, throw on some sexy lingerie, make-up and a come-hither attitude and your fellow will think it's Christmas, Valentines Day and his birthday all rolled into one. However, if you are concerned about the gift part, a nice fragrance to suit him shows you know your man. They also feel that you're marking your territory by giving them a fragrance so that makes them feel even better about the whole relationship.
Otherwise, nothing beats chocolates and a couple of movie tickets (with the proviso that the spare ticket is for you). The other component of this gift is that he gets to choose movie! Believe me, with some movies, that is a huge offering letting someone else choose what you're about to give-up 2 hours of your life for!!!
Good luck and go have some fun. Just don't get caught up in the anxiety of present buying. It's about the thought and having fun together, not how much you spent.
Happy Valentines Day.