Sissela Bok is, in my opinion, one of the most brilliant ethicists of the modern age. Her idea, the Principle of Veracity, states that the truth is always preferable to a lie. Very Kantian, yes...but unlike Kant, Bok's perspective is situational.
The thing about her book, Lying, that I find challenging are her ideas about white lies. The idea that lies are ethical when they "don't hurt anyone" is completely irrelevant because, in truth, we cannot know whether or not our lies (the large and small) damage ourselves or others. "To the extent that we train ourselves to see their (white lies') ramifications and succeed in eliminating them from our speech, the need to resort to them will diminish" (Bok, Lying p.72).
The proverbial butterfly wing flap that causes a hurricane...white lies have consequences just like anything else. It is important in life that we not only do the right thing, but that we know why we are doing the right thing. Ethical systems are important because humans lend themselves so heavily towards justification and because, sometimes, justifying wrongness can be all too easy.
Consider this your permission to say to me "That haircut totally sucks", "I do not think that I will have time to do ______ today", or "Yeah, that dress makes you look like a larger form of mammal than you are".