A. Before you leave, start tying up loose ends (don't wait until the last day to do so!). Change your voicemail greeting and set up an e-mail out-of-office message so that people will know you're away, and arrange for a pinch hitter to handle work that can't wait. Try not to schedule meetings for the day before and after your vacation; that way, you can work without interruptions.
Plan to return home on a Friday or Saturday so you have time to readjust. Or add an extra half day to your vacation so you can unpack in peace while the kids are at daycare.
While you're away, try to resume your family's normal sleep schedule on the last few days of the trip -- you'll all wake up more easily when you get home.
The night before you go back to work, check voicemail from home (e-mail too, if possible) so you won't have to wade through messages in the morning. At work the next day, alternate tough tasks with easy ones to avoid burnout.