Anything from the heart would be great. Cooking a homemade dinner with candlelight and rose petals everywhere. Also of course you can never forget lingire.
Obviously any undergarments, firstly. A romantic homemade dinner with rose petals in the bedroom is always nice, too. If you can't cook have it catered from your favorite restaurant.
Any sort of sexy underwear. Maybe a "toy" you could use. You could do some sort of sexy scavenger hunt or come up with a sexy valentines day game to play.
If you are wanting to give a sexy valentine gift, you can do a number of things. Although, something that I believe is a sexy yet romantic gift is a candle. Candles are also original.