I camped mostly when my children were young, but I can tell you that they loved the experiences. Here are things I know regarding camping that may also translate well into backpacking....
We usually had a hammock for swinging in (they loved those!), and they also loved playing with their little cheapo flashlights & walkie talkies.
The whole trip is a fun learning experience: we talked about fire/outdoor safety, leave no trace philosophy (made a game out of keeping campsite cleaner than how we found it), animal behavior - they especially loved chasing chipmunks and viewing bunnies and deer up close. (lol, I wish this thread allowed me to upload a photo of my boys then age 2 & 3 1/2 hanging out w/deer)
A cozy tent equipped with wall to wall padding & sleeping bags makes an amazing playpen for little kids/toddlers/babies. I vividly remember them happily squealing with laughter as they squished their faces against the screen net to laugh at us silly adults outside. They were happy they could see us, play in their little "play house" and burrow into the sleeping bags only to emerge a few seconds later with their hair all electrified with static. I packed their little backpacks with travel sized and miniature toys/games and they entertained themselves for hours in the tent with those. Some benefits of keeping all toys in the tent is that we could always find all the pieces again if they should slip under a bag or something.
Kids can learn to enjoy all sorts of things: stargazing, fishing, they can help set up tents and other equipment, they can help cook. They can even help carry some of the lighter things and they feel a sense of pride in being able to help out.
My dad took me and my sister camping when we were little, I continued that tradition with my boys, and now I look forward to having grandkids one day and bring them along as well =)
Couple thoughts, as I'm in the midst of figuring this out too (by the way, the article is a good one):
+ A Camelbak Mini Mule has served my younger kids (about 6-7) well. You'll need to limit the amount of water you put in the bladder - the new bladders are about 50ozs, which is usually too much for my kids to carry.
+ I got a Deuter climber for my oldest (almost 8, about 50lbs) to carry some more of her stuff in. Good gear, but the back length is not adjustable. Anything larger would have been too much.
+ I've limited my kids pack weight to about 10% of body weight, which has worked well so far. The kids are mostly carrying daypacks at my kids weights & ages.
+ IRT sleeping bags, I've had good luck with the Mountain Hardwear and Marmot's summer weight synthetic bags.
- I've liked the Tarptent Rainshadow 2 that Oregon Mouse recommended for three people, but haven't had it out in a downpour yet.
- PVC cheap rainpants work great for kids in summer conditions. I haven't yet run into the need for something better to serve as cheap pants in case of a cold snap or rain. YMMV here.
- Please keep in mind that the conditions I'm planning for are around the AT in Virginia from about May-September; we don't go out in known bad weather, and we avoid temps lower than 40 degrees (the rating of our bags).
- My pack weight for a 2 nighter is about 40lbs; more if I'm carrying extra water into a waterless site. I can chop this considerably by (1) replacing my Kelty Tioga frame pack, which is 7lbs, (2) altering my cooking setup (pots, stove), and (3) lightening my first aid kit. The other members of this site were right, a scale is very informative.
Good luck. Please share your experience. I'm definately still learning...
Another thought. If they've never spent a night in a tent, doing it out in the REAL dark of a wilderness area might not be a good first bet.
A backyard test run for sleeping out (with bathroom, lights, and all the comforts of home right there) is a great idea. So is going to an established campground and car camping first.
They don't know what they're supposed to do, an I (who spent a lot more time camping when I was a kid than most) have often had to think about what my kids don't know yet, and then take the time to teach it to them. Basics, like not leaving the zipper open on the tent and that you can pee on a tree, are new concepts.
I hope you have as much fun with yours as I'm having with mine. We're not going far, but we're having a blast doing it.
I just came back from a 2.5 day trip with my 8 and 4 year old boys. This was the first backpacking trip for my 4 yr old. I learned a few things.
1. 4 yr olds have a hard time getting over the fallen logs that you just step over. They also have a harder time with the stream you just jumped over, or the log you balanced across to cross a stream. I had to slow down for him to go over logs, and carry him across some streams.
2. If you carry all their stuff, they will walk as far as you want to with all the weight you are carrying.
3. A glow stick or cylume(sp?) light works great as a night light. I get one for every night and hang it in the tent for them.
4. Quick dry clothes are a must, especially when they fall in the freezing river over their heads.
5. Bring candy. I like to bring a mix of hard candy and put it in a baggy in their pack.
6. Bring mittens and a warm hat for them.
I've taken a vow of poverty. To annoy me, send money.
Oh, I just remembered something in response to your post. The pajamas we buy for our kids are often lightweight fleece. We used one of my 6 year old son's pajama tops as his insulating layer on the last trip, and didn't have to buy anything special.