I can't agree more with Seat 2A. Though there are differences in shuttle bus drive commentaries, it is rare that the shuttle drivers give very little if any commentary. They all love the park and drive there multiple times a week. They love to share their passion about the park. Having been on lots of shuttle buses in Denali over the years, I have to honestly say that Seat 2A gives one of the best, if not the best, commentaries I have ever had on a shuttle bus. If you happen to get the rare shuttle bus driver who doesn't give much commentary, hop off at the first rest stop and wait for another shuttle bus with room on it. But I really don't think it will be an issue.

Be sure that the kids each have their own binoculars. Also be sure they each have their own camera, if only an inexpensive one. Also be sure you bring triple the batteries that you think you will need for any entertainment items you bring.

Bring plenty of food and drink too. You can refill water bottles at Eielson Visitor Center if you take the shuttle bus.

I would book the shuttle bus to Eielson and decide the day of the trip how far you will go. The area between where the Tundra Wilderness Tour turns around and Eielson is prime bear habitat so your chances of seeing bears increase if you take the shuttle to Eielson.

One huge advantage to the shuttle bus is that you can get off the bus if/when the kids want a break or if one of them acts up, etc. Then walk along the road for a while and catch another bus as it comes along.

Also, when you first get to the park be sure to go to the visitor center and pick up Junior Ranger backpacks for the kids. This will help to keep them occupied.