Tbh I could care less about Valentine's Day and I really didn't feel like writing this, but I figured I'd better. So yeh
Dean:
He was unsure of what was supposed to happen, considering he's never been in a committed relationship with anybody around this time. So basically, the night ended in hot sex. (Oops)
Sam:
Sam had previous experience with this, so it was perfect. He took you out to dinner and afterwards, you went star-gazing. Best Valentine's Day ever.
Cas:
He didn't really understand what was supposed to be done, so you had to help him through it. You ended up having a wonderful time anyways.
Crowley:
It was like any other day for the most part, but you sat up later than normal, drinking together, discussing things that you found important, and then things went a little south if you catch my drift ;)
Gabriel:
First there was candy. So much fucking candy. And the flowers. So many fucking flowers. And the alcohol! So much FUCKING alcohol. Gabriel succeeded in getting you smashed and lucky for him, you were a happy drunk. You spent most of the night dancing together, and by the night's end, you had sobered up enough to snap out of your drunken state and make the decision to end Valentine's Day by doing the dirty. ;))))
Kevin:
He bought you a rose and a box of chocolates, and you spent the day cuddling together because he knew it was one of your favorite things to do.