I've done 3 hiking seasons now with my two girls, now 10 and 14. We've done a couple of 4-day trips now. We discuss what they are to do in case I get hurt, and I encourage them to work out map details with me.
They're more comfortable with a phone along, but the areas we hike have very limited to no coverage at all. Since I've started with some solo hiking, I'm considering a PLB, but haven't been able to swallow the price tag yet.
Frankly, I would be comfortable with either of my girls on a long trek, but I'm not going to drag them out there before they are ready. If they can get excited over a more rigorous trek, then I'll have them so some planning with me and we'll go. I don't want to wreck their enthusiasm for backpacking by pushing too hard.
My 14-year-old and I would love to do a long trip through SE Alaska via the ferry from Bellingham, WA, but I'm not convinced we're ready yet. That's on the back burner for now.