re the tool at
You can ask an infinite number of comparison questions - I'd like to hear what people have discovered that might be important but not obvious to ask:
TAKING EARLY? CONSIDER REDUCTION IN SURVIVOR BENEFIT
I compared the loss of benefits if the higher earner retires at 69 instead of 70, and the lifetime difference is 1% for us. Seems trivial, and gives almost the same amount up front in the age 69 year while taking it back slowly over the rest of our lives. So think of the Present Value to take a trip or something while healthier.
HOWEVER if the survivor lives longer than expected, for us the reduction in survivor benefits is 6.2% per year. Living longer is all "bonus" money, but having a reduced bonus might be significant.