Definately dress to impress on both days. And as everyone else has said give every house a chance. Every house has its Ups and Downs, geeks, partiers, trouble makers etc. In all honesty sorority life is what You yourself make of it. I've known girls who have been in the "big popular houses" and they didnt think it was too great. I've known some who loved it also, just like I have known girls from the smaller "less popular houses" who loved it, but some who ended up not to crazy about it. Keep being open minded and don't let campus reputations possibly cloud your judement. Big thing to remember the Active members are just as nervous, if not maybe more then you are. They have to impress you too. Have fun and hope you get whatever house you want!