Book a flight that connects to the last flight of the day for your city in CA. When you arrive in MSP miss your connecting flight..."I was sick in the bathroom"...once the door is closed stop at the gate and explain you missed your flight (it's important you get on the standby list within the hour of you missing your original flight) and standby for the first flight the next morning.

This plan does involve some risk as now NW isn't required to give you a seat or promise you will make it to CA on any flight the next day (if all the seats are full) but if your schedule if flexible and you have the courage to try it it could buy you 12 hours in MSP with the family.