The poor are another separate issue. They need to be close to jobs or at least have a way to get to jobs easily. When I was poor, I didn't care to live in a cachet neighborhood, I just needed to be able to get to my job with reasonable public transit and I wanted to feel the area was safe. Of course, given the alternative, I'd want to rent a bungalow next to the beach for cheap, but it's not a necessity and it's not a necessity to live next to one's job.
That said, I would love to see more mixed use zoning.
Gross. I get that some people get to places in their lives where they don't want to deal with diversity, but I don't want cities to turn into places like that. Retirees (those who do want to stay, and don't want to live in a retirement community) are a part of that diversity. Shipping anyone off involuntarily (or even semi-involuntarily, in the case of ridiculous housing cost swings) is completely unacceptable to me.
And I don't think homogeneity is gross. Do you think Nigerians feel gross, or do you think the Japanese feel gross? It's neither better nor worse then heterogeneity.