Catherine, I think it is a decent idea for you to have life insurance with the idea that your death not only removes the significant income for your household, it would leave your spouse unable to pay the debt of your household. This protects him.
As fir the 3 million of your son’s policy, I would have to put pencil to paper to determine if that is excessive. But since he has small children and he probably wants to provide a college education for them, and also he lives in an expensive part of the country, just off the top of my head 1 million or two doesn’t seem too much.