Most people leave everything to their spouse. If they are in a second marriage, they may allocate a substantial part of the estate to their children from the first marriage. Watch the tax costs for assets bequeathed to anyone other than a spouse. You may sell or give them away before you die. Here's where you get into whether your assets should pass directly to heirs or be put into a trust.
Trusts are usually the answer.
For now, if your estate exceeds the legal threshold and triggers an estate tax, you need to consider trusts. Even without taxes, most people will still need trusts in their will. Assume your estate will be larger. The size of your estate is certainly going to be different when you die than it was when you drew up your will. If you have managed your finances well, your estate is going to be bigger.