I will be 60 in November, and I'm tentatively planning to retire in December. The health care thing, and when to take Social Security, are the tricky parts and why I have a little bit of doubt. And I've been planning for this (assuming I'd be forced out in my 50's because that's what all the big tech companies do) since I was 30.
I'm thinking of taking my employer's COBRA plan for a year while living off my savings so I have virtually no income, then after a year of that switch to Obamacare. Hopefully they don't means-test it; just see that I have no income and give me the maximum subsidy. Part of my retirement package is a "Future Health Account" that should cover those overpriced COBRA premiums for almost a year and a half, so I'll burn thru most of that and save the rest for Medicare Part B.
As to Social Security, I'm starting to think taking it early is the right plan. I'll get smaller checks, but more of them; the break-even point is probably about 90 so I'll have more money early in my retirement while I can enjoy it and less at the end when it's all going to a nursing home anyway, and it will help preserve my cash while I'm waiting for Medicare eligibility.