One of the biggest factors which will determine whether or not someone will enjoy camping as an adult is how much they enjoyed camping as a kid. So, basically, you wield a great amount of control over the attitude your kids have towards camping for the rest of their lives. No pressure.
The first thing you should take into consideration is how easily accessible your camping spot is, by car. While you may understand the point of hiking for three hours just to get to a beautiful and natural camping spot, your kids probably won't. Save yourself the frustration of listening to "are we there yet" a thousand times by ensuring that you camp somewhere that you can easily get to in the car.
Another reason for a vehicle-accessible camping spot is the fact that your younger kids aren't capable of hauling all of their own supplies. This means that you'll be taking on the extra weight of their supplies, which is likely to reduce the amount of fun you have and increase the amount of pain you suffer.
Whenever possible, plan to camp somewhere that will allow an open fire. Sometimes, the difference between a successful and unsuccessful camping trip is nothing more than roasted hotdogs and marshmallows and, of course, s'mores. Invest the minimal amount of money necessary to get actually roasting rods to minimize the chance that you have to intervene when your young children decide to play Star Wars with flaming roasting sticks.
You're going to want to ensure that your kids to be as comfortable as possible...just to preserve your own sanity. Make sure you bring a variety of clothing, in case the weather changes, and consider investing in an air mattress for them to sleep on. Barring that, let them pick out their own sleeping bags. While the particular animation personality on the bag has absolutely no impact on the comfort of using the bag, it seems to make a difference to kids.
Also, remember that they will be out in the wilderness and away from the security of their well-known home. Even if the "wilderness" is nothing more than a national park with extremely modern conveniences, it won't seem that way to your kids in the middle of the night. While they are still young, you'll probably want to invest in a family size tent so that they can sleep near you. Older kids may want their own tents, however, so it's best to talk to them in advance.
Finally, run through some basic safety lessons with the kids. Don't scare them if it's not necessary, but you should talk about fire, snakes and insects at a bare minimum. You may also need to discuss bears and other wild animals. Again, if you're going camping somewhere completely devoid of truly wild animals, don't give your kids nightmares by talking about bears, mountain lions, etc. Prepare them, however, to deal with anything that they may come across.