Although I am a little more keen on the Spring Break idea than the Valentines (mainly because Spring Break can go a lot of places), the idea of an "Anti-Valentines" event just doesn't sound right. It just sounds so negative. Not everybody thinks Valentine's Day is evil, and people's perspectives about it can change over time. And since there is a common notion that anime otaku are "not-so-sociable" people, having an "Anti-Valentines" event may just serve to reinforce that reputation.
By sort of the same token, people who feel bitter about Valentines will prolly not participate in a plain "Valentines" event, or otherwise would be participating grudgingly. At least most people feel pretty happy when they think about Spring Break.
Also, Spring Break will give you a lot more time to prepare, as Valentines day is coming up in 1 and a half months.
Anyway, those are my thoughts, though the idea of a new event would be great, and I'm glad Electron Blues is taking charge of this. However, I would like to provide a few suggestions to make a new event effective; take 'em or leave 'em:
Most importantly, you may not want to have the new event similar to FCW2002-3; even though the season is different, the approach to it may run the risk of being too similar, so you may want to add some kind of twist to the event, or do something quite different. I think I've mentioned these ideas somewhere else, but for example, you can have a fan-art swap, a beauty contest, or even a comic jam. Maybe even have artists participate in groups.
Heck, you can even have totally off the wall events like a trivia show or a murder mystery/scavenger hunt, or even *gasp* Keenime Survivor or Iron Chef keenime-style. Heck, for Valentine's Day, you can even set up a fake dating service for webcomic characters. I'm just throwing out some wacky ideas that may or may not sound interesting to you.
Keenime FCW is something that was done already by other people in Keenspace/Spot; instead of us trying to be novel, the event was just sort of an easy starter to get people to participate. The point is, feel free to think of events that have never been done before in the history of keenspot/keenspace. Feel free to be creative and crazy.
Also, whenever any of you are ready to go ahead with an event, make sure to tell me so I can prepare to help you promote the event on our dropdowns and forums, etc.