It really just depends on the person. Some like classy, rich dinners, while others like old-fashioned, straight-from-the-heart kind of things. I know some people that absolutely despise Valentine's Day and anything that is related to it.
So, I just recommend anything that you could come up with that may interest the one you are trying to swoon. I cannot share any ideas because I literally have not gone out of my way to do this sort of thing, or have been confronted by the opposite gender (or same gender). The most I have done is hug the special someone from behind and ask this someone to be my Valentine's, which was a complete success.