skygiants

I think Gokusen is classified as josei because sweet little girls are not supposed to like all that fighting stuff and hardcore little boys are not supposed to like all that non-fanservice-based romance stuff. Personally I would give it to any 13-year-old-and-up regardless of gender, but hey. As for why Yotsuba&! is seinen...the world is a mysterious place.

I myself just got the first-four-volumes omnibus of Cardcaptor Sakura, only having seen the anime, and it is just as sweet and charming. It is also girly as fuck, seriously the main character changes into different cutesy outfits every time she goes up against an opponent of the week, although that is more the fault of her fashionably inclined/canonically-crushing-on-her best friend. Also, 3/4ths of the main male cast is either gay or bisexual. (The fourth is her dad.) All in all, if you're looking for shoujo, it's hard to beat one of the classics.