For a couple who own property it is fairly standard to either buy it as tenants in common or, if held jointly to sever the tenancy and create tenancy in common, where each party owns a share (usually half each) of the property(s).
Each then has a Will drawn up including a property trust giving the other the right to live in the property after the first death (and in a well-drafted Will the right to downsize etc.). The right to occupy could be for a fixed term, to give time to find somewhere else to live, or for life (or until they go into care permanently). After the second death each share passes under each Will. This makes sure at least your half is guaranteed to go to the people you choose, even if the other person remarries and changes their Will.
The pros are that at least half of the property will go to the people you choose and vitally that your half of the property will not be used to pay care costs if the other owner needs care after the first death. If concerned about divorce, bankruptcy or spendthrift tendencies of the children you can use a discretionary trust.
The only downside is that it obviously costs more than a basic Will or I would not recommend trying to DIY it.