my best advice is not gear, but altitude effect.
assuming your kids do not have previous altitude experience, here is what I learned in 1994 - one son age 13 no problem, other son age 10 altitude sick at "only" 9,000 feet.
This factor can be huge and overwhelms all other considerations. Of course, only way to know is to do it, but extended dayhikes at altitude should be done first to see if overnight can be tolerated and/or amount of slow acclimatization needed. (as you mentioned)
Just to add to what Harvey said...I have absolutely no problems day hiking to any elevation in SoCal. However, if I add just a few more hours to the equation I have had problems down to as low as 7,500'...June Lake. Unless you have put it to the test you will never know for certain.
