I think that the way JK wrote about the different students from the houses in he books is really good. Its kindof branching out on what we know, what we think we know and what we want to be true.
i agree fully that it would be nice to have a couple of 'steryotypical' students from each house. a hermione type figure for Ravenclaw and a neville type charicter for Hufflepuff we have draco and harry for the others.Maybie JK is showing that modern children don't fit into the typical steryotypes of yesteryear. She is showing that the qualitys can be there, but in a totally different aspect to usual. like luna, being wise and wavey but she marked the door in the room didn;t she? ( or was it hermione?ahh its late) and cho maybe annoying, but she is also usually reserved, and studious. she did work really hard in the DA. and although Neville isn't the natural choice for Gryffindor he has courage and stands up for things when he needs to.