Married Couples Estate Planning

The three documents every married couple 'should' have is a power of attorney, advanced health care directive, and a will (a set for each spouse). A trust is also good if you have real property. 

More realistically let me tell you how I've seen this work out in life.

The durable power of attorney and advanced health care directive mainly help your children, empowering them to make decisions if both you and your husband become incapacitated. What most people do not anticipate is that their spouse will become incapacitated and then they will also face a health crisis shortly thereafter leaving the children (or other trusted family/friends) to make decisions. 

Common situations, that I've seen, one spouse can generally do everything needed without these documents, if the other becomes incapacitated.

There are a few exceptions to the 'spouse can generally do everything' rule: there are special rules for retirement plans, jointly held property, and accounts held in one spouses name only.