For a 1st time out backpacking, find a destination about (or a lil' less than their normal dayhike range) and do a simple overnight to start off.

What are you referring to by "weekend activities"? Are you camping and dayhiking?

I have a much younger brood (8, 4, 2), but we are starting off with finding State Parks (NPs, NFs too) camping and dayhiking around. I recently took the 2 older girls on an overnight and everything went fine.

Just start small/short trips and expand from there as you and your family gain confidence and skill in being in the wild.