Would I be able to travel on a plane for a family vacation, 4 weeks post full tummy tuck and breast lift?

This question is best to be answered by your board certified plastic surgeon. I typically recommend my patients to avoid any travelling for about 4 weeks in case of complications and to allow enough time for recovery. Best of luck with your upcoming surgery.

At 4 weeks after surgery you should be able to fly safely as you described.  Be sure to rotate your ankles and walk around a bit if possible.  When on your vacation please note that you will likely not have your normal energy level back and may tire easily.  If you are planning an active vacation, be sure to factor in time for breaks.