As the poster who said, a couple of pages ago, that I thought I could have both an incredible family and an incredible career, I want to jump back in and say that I'm not offended at all by the fact that Teresa Pitman disagrees. A lot of it has to do with word choice: can you "have it all" and still "trade off"? She speaks from the lens of her own experience, as do I, although my experiences are observational and hers are actual.

Opinions on this issue are driven so much by individual experiences and unique circumstances that I can't imagine all will ever agree. It's all about where we come from.
Here are a few factors that shape my point of view:
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The quality of the mom is so much more powerful than whether she is SAH or Working. It's all about the woman. We all know crappy and sublime SAHMs, crappy and sublime Working moms. It's the personality traits and characteristics of the woman that shape how the kids are going to turn out. It's less about how she spends 9-5 and more about how she engages the kids in the hours they share.
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Income level often, not always, but often drives this decision. The same woman who would elect to be a SAHM at an earning power of $30K would likely consider working tomorrow at an earning power of $300K. Always true? No, definitely not. Indicatively true? Probably, yea. This is amplified if DH's earning power is substantially lower than DW's. The difference between a family income of $60K and $360K per year is not messing around. It's a whole different life for the kids, as Dave Ramsey puts it, it's "changing the family tree" money. It's essentially the decision to trade off daytime with the kids (easier if they're in school, but still, daytime) for lower stress and more luxury and (often, not always) a more harmonious marriage, because you're not fighting about money.
Imagine what it would be like if you never had to worry about money - if you could just do what you wanted, when you wanted, if you could own your house flat-out, if bills were just annoying and never worrisome, if you could fly to Italy tomorrow and not really feel it in your checking account at all. I'm in a pretty rarefied environment in this city, but honestly, this is the tradeoff that some of my female friends face as they approach their 30s and think about having a first baby. The choice: Work, and lower the stress, hit your longtime goals, give your kids material advantages. Stay at home, and transform your lifestyle, maybe advantage the kids emotionally, maybe define yourself a whole different way. It's not that either is ethically better or worse - it's that it's a substantial tradeoff.
This is different than if you're choosing between lower-paid jobs and staying at home. The equation of the tradeoff changes entirely.
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American women in 2009 should never feel guilty about, or make excuses about, wanting to achieve professionally. The world has fundamentally changed. Five thousand years of subservience have given way to an idea that women can be professionally equal to men, and this was a swing that occured over a fraction of the time, just 50 years. This shift is enormous and it's going to take culture a while to catch up. Elementary-school-aged girls are seeing an entirely different world right now. Personally, I see value in my future little girl knowing that (a) mom loves me and (b) mom does smart stuff during the day, but I know that I am very important, and (c) that's why grandma and my nanny are at my house when I get home from school, and them Mom is home after that and (d) I can do anything I want in the whole world, just like Mom does. I think this is how the Obama girls feel about Michelle, and how the Osteen daughter feels about Victoria, and I could give about a thousand more examples. That's how I want to be.
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There's a lot of natural defensiveness on this point. Sometimes, I'm not sure what we expect people to say. 
I mean, do we really expect a woman who stays at home to say, "sure, you're right, it was a mistake to give up on my career and spend most of my days away from other adults, and make myself financially vulnerable if my husband has a midlife?" Do we really expect a woman who works to say, "sure, you're right, it was a mistake to work and miss important developmental milestones, and my kid probably misses me when I'm gone, and why is the money even important to me anyway?" I mean, we don't really expect that, right?
It's all about the individual and unique circumstances.