I'm probably a bit different from the norm, but...
For relationships, personality is the only thing that matters: I don't really care about how someone looks, so long as we get along well. On the other hand, I prefer someone attractive for sex (for obvious reasons). Unlike most people, however, I've found these two things to be discrete categories-- I can be in a relationship without a desire for sex, and I can have sex with no relationship at all (also include the middle grounds).