"Roommates wanted: hot college girls"

this is a hypothetical about personal preference. are we allowed to have our own personal preferences?
I like the color green a lot. others like blue, and that is okay, but are they allowed, by law, to ask me to not like green?

So, I own a big house near a large college, with a few extra rooms and I could set them up with double locks and rent them to college students. I got gig internet, large TVs with movies and games, workout area, 3 bathrooms, two fridges and a freezer, and ample parking, within a decent walking distance to campus.

is there anything wrong with me deciding exactly whom I will take money from in exchange for a key for a room, access to kitchen and bathrooms, and parking, and dividing the utility bills?
If I said I only want to allow pretty college women only, my personal preference of who I personally feel are pretty, is that discriminatory?
Normally, one will conduct interviews to see who gets to rent a room, as in, if they are obviously a drugged up crack user, and maybe not seemingly reliable enough to come up with monthly rent, one would choose to bypass that person and look to the next.

If I would rather see hot college women roaming around my house, than say, nerdy fortnight college males (or anything else I simply don't want to see) does that break any laws, or am I just embracing my personal preference, as I am when I paint a wall green because I prefer it?

Addendum: what if I also narrowed it down to hot Asian only, or black, or blondes only etc?