Dating one's friends

Seems as if I started going out with Ann... But this post is going to be rather theoretical.
It's provoked by two Misas (Rakova and Synackova) who were wondering how one can date a classmate one's been going to the same class for 7 years.
Well, either you haven't known the person very well till recently or you realized just recently the person attracts you. I'd say about at least cca 10 of my classmates that I don't really know them, only vaguely.
Misa S. said (when we recently talked about it in a tea room) she behaves differently to people she talks to cause she finds them interesting and differently to those she wants to date. Well, I'm rather different - I behave to all unknown people as if they were interesting (after all I think everyone is somewhat special). Logically I can only date someone who I already know :-)
Of course, if you only care about physical attraction, then Misa's attitude is optimal. Yet I believe that to develop a good relationship (no matter if friendship, partnership or whatever) you must know the person.
Yer even if you know each other, it doesn't mean your relationship will be satisfying.
Today, Ann told me two things that made me think. First, how will our relationship continue, when the first love fascination ends? And second, that we hadn't talked about anything sensible in past few days.
I'm thinking about it and about the possible solutions. I've already told her we should get to know each other more. I must talk to Ann about the other thoughts that happened to me since I'd seen her.