re: So how do you approach your parents about their estate plans?

I am always surprised to hear when a particular topic might be offensive to a family member. Either I could not care less about offending my family (which I don't), or we are close enough for it not to matter.

When my mom was dying years ago, I had her power of attorney to handle her affairs. She was divorced from my dad for some 20 years, but they both held interest in a private business - roughly 48% of the business combined with the remainder held by a different family. My mom had gotten $0 from it from the beginning while my dad had been paid "attorney fees" for years, which I thought were really share of profits. So I called my dad out on it and basically coerced him into selling our family's block of shares to the other family. He did not speak to me for a week, but he came around and we sold. Our relationship is just fine now that the issue is well behind us.

Maybe I just don't give a crap about offending someone, but I think these sorts of issues are too important to pussyfoot around. Just invite them to dinner and discuss your concerns. I can't imagine why anyone would be offended by something like this, but if they are, they'll get over it.