Assuming you are married under community property rules, it does not matter in whose name the property is recorded, half of it belongs to each spouse.
Upon the death of a spouse, the half that does not belong to him/her goes to the deceased spouse's children unless there is a will. There is a limit, however, to the proportion that may be willed to the wife if the deceased has children (as a general rule, no more than 25%). Therefore, with the proper planning, the wife may get 62.5% of assets [50% + 1/4(50%)].
The wife is not considered an heir of her 50% of community property. It belongs to her from the time it was acquired during marriage. Therefore, she doesn't have to pay any estate taxes. The children pay taxes on their share. If they reside abroad, the 50% surcharge applies.