To me Valentines Day is an utterly shameless consumerist effort to force people into buying stuff they don't need, all to force a manipulative and shallow interpretation of romance on those with partners and to make those without feel pathetic and lonely.
It is easily my least favourite holiday, and that includes the stupid ones that seem arbitary at the best of times, like Guy Fawkes Night or, I dunno... Flag Day or something.
Agreed on Valentine's Day. The SO and I ignore it, on the grounds that if we need to be told to do something romantic, it isn't romantic any more.
As for Guy Fawkes' Night, that's a bit different. The way I put it is that half the country celebrates that a man got caught before he could blow up Parliament and the King. The other half celebrates that he got so damned close...
(Also, Guy Fawkes' might have a different explanation. Samhain was the most important night of the year, in pre-Christian times. The old year ended. Five days later, the new year started, and fire was a major part of the ceremony. And five days after halloween is... yeah. I can't help but think that has something to do with it...)