I thought JK was gearing up for Ron/Luna, myself. Luna seemed to have a bit of a thing for Ron, then Ron came out with a line somewhere along the lines of showing a fondness of sorts towards her (can't remember exactly, might've been in HBP). Luna would've fit in well with the Weasleys too, lol. And I totally thought that Ginny would be with Neville in the end. He went out of his way to protect/defend her on more than one occasion, and she tried to boost his confidence. It would have been very sweet, and a nice bit of character development for Ginny (something she was very sorely lacking), in that as a kid she pined for the famous Harry Potter for superficial reasons, but goes on to realise fame/talent/popularity aren't the qualities she should be looking for in a guy, and that the sweet, bumbling dude who trod on her toes at the Yule Ball might be just who she is really looking for. <3
But no, she had to retain the Mary-Sue persona that was rammed down our throats from OotP onwards.... sigh!