It seems to me the most important thing to remember about when to collect SS, is that most in cases the benefits are designed to be actuarially neutral. Meaning no matter what you choose, it is not a bad choice.
The main exception is the younger wife, who made less money than her husband. Given her much longer life expectancy (nearly 3 years at 65) plus age difference, being able to collect his full retirement upon his passing is big deal.
Personally, I'm waiting until 70 not only for longevity insurance but also as protection against elder abuse. My grandparent's estate was looted for a least a million, by a crooked trust officer who took advantage of my grandmother's dementia to steal millions. I figure without kids or a spouse, I'm particularly vulnerable, but even if I had both there are no guarantees. So while it is possible some gold digger, could loot my assets, it is a lot harder to steal my social security check.