Having never done anything close to a rafting trip, we opted for something easy - the 13 Mile Scenic Raft Trip and signed up for the 8:00 AM trip.
This is a relaxing, fun, and easy way to see the Jackson Hole Valley. Our rafting guide was a young lady name Karen who was a wealth of information with a terrific sense of humor. You'll see quite a bit of wildlife along with some beautiful views of the Tetons. Total time on the water was about three hours so if you grab the early morning trip, you'll have time to get back into Jackson for lunch.
The trip is more than suitable for younger children. If you take the morning trip, dress appropriately as it was cooler on the water. Bring a hat and sunscreen along with your camera/mobile device. You can bring a small pack along so that you can bring water and snacks (it is a three hour trip). Next time, we'll try the white water tour as my family now has the "bug" and wants to give it a try.
I would definitely recommend this as a good "first timers" try at river rafting.