After reading 9 books on Social Security, I finally found the best one:
How to Make Your Money Last by Jane Bryant Quinn.
It is up to date as of 2016, and covers several other related topics.
Prior to the 2015 Budget Act, strategies for couples to consider were 'File and Suspend' and 'Restricted Application'. The 'File and Suspend' loophole closed about May 1st, 2016. The other loophole, 'Restricted Application', which allows a person to claim half their spouse's benefits without claiming against their own account, still stands for those born in 1953 or earlier.
For both singles and couples, when to file is an important decision. For a single, there are 9 choices; for a couple there are 81 possible combinations. The most important consideration is life expectancy, something most of us don't know with any certainty. Mike Piper and others offer recommendations and considerations.
This is a complex problem with many interactions, including life expectancy, taxes, future investment returns, inflation rates, and Roth conversions. There are Internet calculators and financial planners available, but they vary greatly in quality.
We were surprised to discover an initial cash-flow issue. Social Security payments are paid the month after the current month, on a date based on which third of the month your birthday falls. Medicare costs are due the month before the current month, that is, 2 months before the month's Social Security is received.