I like trying to plan for these kinds of trips. There are good ideas already mentioned. There are Wyoming Topographic Recreation Maps on amazon that give a good list of things that might be interesting and roads to get there. Fort Robinson is pretty cool. Its worth a stop. I think Thermopolis, like was mentioned in another topic is a place that is pretty kid friendly. You can swim in the hot springs, and the museums are pretty cool. It cuts a couple hours off the drive to Yellowstone. This is where my ideas start to add more miles, but if you go north through Hyattville there are some cool rock formations and petroglyphs, further north towards Shell and Greybull there are dinosaur footprints and sometimes you can find fossils in the BLM, then you can loop back over the Big Horns, all three paved routes are cut into the mountain and they have signs showing the different rock formations and ages, on the east side there some other things like Fort Phil Kearney, then you go east to Devils Tower and other things already mentioned. That could have been written better, but its some ideas.
