Wow, I didn't realize when I asked my question that I would gather so many interesting replies! This is a great discussion, I hope it is ok with the moderators that we are a bit far afield from the topic of marine life
I am also not a fan of "Political Correctness" because I feel it causes us to focus on finding a list of words that we can prohibit instead of helping us to foster understanding between different groups of people. I think it is useful to stop using derogatory phrases obviously but it doesn't help us get any closer to the people who have some difference from us and as you said so perfectly, faced with trying NOT to say the wrong thing you end up feeling awkward and "treading carefully".
I wonder, do you ever feel comfortable enough with your friends who are people of color to talk about this awkwardness with them and have the chance to hear what their perceptions are? This is the kind of thing that I have found more useful torwards having closer friendships and gives me the chance to broaden my perspective about the world.