Good point. In the wills I write I designate beneficiaries at least three levels....first to, then to, and then to... I think most attorneys do the same.
Especially in case both spouses die in a common accident.
Some folks because of the size of their net worth have done major estate planning via living trusts, remainder trusts and gifting to minimize taxes. There are wills and pour over wills and a ton of strategy that needs to be looked at in lite of the new tax laws. It all depends on the size of your estate. If nothing else please do a will tommorow if nothing else and then get serious about all the details on this site.
WARNING...Putting chrildren as co-owners has a serious pit fall. If that child has a judgement placed against them there goes your house. Bruce Williams talks about this on the radio all the time. It also deprive them of the stepup in value on your death.