1. I would recommend you Flight to buffelo and rent a car and go by Peace Bridge in Buffelo and come back through the same Bridge.
It is easiest way back. It took me 1 minutes to pass U.S .immigration officer when I was back to U.S. I just back two weeks ago. Staying in Canada for 1 week. We are exactly same situation as your friends, except we only have 1 kid, who is also a U.S. citizen.
2. Never take a flight to Canada directly.
3. When you leave U.S., go to U.S. immigration officer and they will stamp your passport with a date.
4. Keep your all I94 and form 797 ready, especially the current one and your passport current.
I think that is all.