I think I agree with all 3. Or maybe have some disagreements. I'll need more details, though.

Here's your summary:

Chez: Ethics derived from values; goodness based on helping others.
Doug: Ethics derived from values; goodness based on helping yourself.
David: Ethics determined by society.

I think personal ethics (morality) is determined by what increases happiness. It's comprised of what increases your happiness, as well as what increases the happiness of others. Since we live in a shared reality, we have to cooperate with each other, and come to a consensus about what things are good or bad for the society. So, I think I agree with all 3 of you.