Don't get me wrong, you can make ends meet and find a somewhat decent place in those cities. But like I mentioned,$3,000 a month in the Bay Area suburbs gets me a 1500 square foot three-bedroom house whereas $3,000 a month in Atlanta gets me two houses or one gigantic house.
Not to mention most people don't just want to live, I'd like to be able to have a nice house, save money for retirement, I don't want to be house poor just to say I live in New York or LA or San Francisco. All those areas are great, but unless you're bringing in big money I wouldn't advise it.