I would say the minimum should be 10% including the company match. So if your company matches the first 4% (as my company does), you should invest 6% of your own salary to get to the 10%. Even if you think you are already set for retirement, you still want to contribute enough to get that company match as it is free money you don't want sitting on the table.
That said, nobody ever complained about having TOO MUCH money for retirement, so save as much as you comfortably can. Even if Social Security is still around, it's a buffer, not a means of retirement.
Absolutely. It would be crazy not to get all you can out of a company match, if it is available to you.
"Even if Social Security is still around, it's a buffer, not a means of retirement."
Yes, it should be a supplement, not your entire retirement plan (if it is, you're in trouble!). But I think for a lot of people, Social Security does represent a significant portion of their planned retirement income. So, not having that, or having it being greatly devalued by inflation, just adds to the challenges many people will face.