Anyone marrying later in life needs to keep estate planning front and center in their financial discussions.

One partner likely will pass away first, so discussions should focus on who will inherit what. Often a person wants to leave many of his or her personal assets to children or grandchildren, while still providing for the surviving spouse.

Couples also need to keep the concept of "elective share" in mind. Each state has its own rules as to how much a spouse is entitled to inherit, regardless of what a will says.

Couples might consider a Qualified Terminable Interest Property trust, nicknamed QTIPs, through which the surviving spouse receives income from the trust's assets for life, with the principal left to someone such as the decedent's children, Montanaro says.

Couples also should plan ahead in order to avoid conflicts over touchy issues like heirlooms or sentimental property. Martin advocates that all children inherit something when their parent dies. "Make sure everyone gets a hug from the grave," he says.