Things I've done or am in the process of doing for myself, spouse, kids:
retrieve Social Security earnings statements from ssa dot gov
request new hardcopy SSN cards
verify IRS IP pins are current
check safe for official copies of birth certificates and any other key documents (marriage license, etc)
have encrypted photos of drivers licenses, passports, and global entry cards stored on phones and in secure cloud storage
renew passports if necessary and get passport cards
Anything else?