Some of this may be because this is my first and he is only a month old, but I don't really nurse around people in the first place. If I'm around my mom, I do it and don't bother to hide...she's the one who taught me how. My husband, obviously I don't cover for him lol.
When I am with family it seems to be understood that I just excuse myself to a bedroom. I don't want to make people feel uncomfortable, it's more that than a modesty issue. I also prefer to be alone because I'm new at this and it's easier when I don't have to make sure everything stays covered.
If it's just one female, like my sister or I have a friend over, I will just latch him in another room (because I'm bad at not being able to see that) and then cover up and return. My friends are also mothers, so I feel more comfortable doing it in front of them.
I think it's fine to breastfeed in public, covered or not. I'm saying that mostly because I think it's less obvious when you don't cover up. Whatever the mother is comfortable with. Now that I think about it, I've never really seen a woman breastfeeding. Maybe 3 or so occasions in my lifetime, that might explain why I'm not very comfortable doing it.