We will probably act like a couple would. Dinner out someplace nice and romantic...with cards and maybe a small gift for each other. (Not necessarily candy or roses but probably something more useful...a nice new shirt or shoes, etc.)
The main issue I think we'll have is that most restaurants around here serve a special "Prixe Fixe menu for two" on Valentines, instead of their normal menu. We'll have to do our homework and find someplace that isn't doing that...or at least allows a modification for three.
(And add the fact that I don't eat red meat, and C doesn't like seafood...needless to say we got work to do!