"[F]or a 65-year-old couple, there's a more than 60% chance that one of you will live to age 90. So delaying benefits for you and/or your spouse to have the potential to receive a higher benefit amount for a longer period of time is likely to be the better financial decision.... [E]very year you delay taking benefits beyond the earliest possible starting point will boost your annual payout by as much as 8%, and this figure is adjusted for inflation.... A guaranteed return of up to 8%, in real terms, is not easy to find in the current economic environment, especially on a risk-free basis."