If you HAD to change one thing (or more then one if you want) in the series what would it be?
Hm... Well I think that something I'd do is try to include all the side stories and have them be as faithful as possible to the original text. I know they did a fair amount of them, but I mean, it's thru those that we see Kaname having part time jobs, that Kyouko is actually the 'bad influence' instead of this more innocent sweet girl we know (I just mean this in the sense that there's more than one story where she's either already drunk or getting there XDDDDD), definitely wouldn't water down how much of an asshole Sousuke was at first... Um...oh yeah, would defs have Yan's relationship with Tessa being far more obvious than like, almost nothing XDDDD
Just include more to help flesh out the characters a bit more so that those who don't/didn't have access to the original novels for any reason would still know them as well as those of us who were lucky enough to have that access. Other than that, there's really not much that I would change personally.