Highway 2 would be my choice of routes thru Montana, I also like highway 12. the interstate is my last choice. Now I want to ask everyone to stop dis'ing eastern Montana. There are lots of recreational opportunities. Starting with the little town of Ekalaka on highway 7, the first county museum in the state, awesome paleontological exhibits. Then a few miles north to Medicine Rocks state park, wild sandstone formations with dry camping and lots of hiking/climbing. Then North to Wibaux on 7 then hit I94 to glendive. There is a dinosaur museum there then out to Makoshika state park, dry camping again but some really wonderful badlands to explore. All of this is on the Montana dinosaur trail. Oh while at Glendive you can fish the Yellowstone river or look for Montana moss agates. Then on north and west to Fort Peck Dam camp on the lake with hookups. Head for highway 2, plenty of fuel stops and rv parks. We overnight at the city park in Malta for $3, big cottonwoods for shade, but Havre and Cut Bank have rv parks, I think some of the other small communities have rv parks also. Thru all this there is great wildlife viewing and bird watching opportunities. Oh and I can't forget the sunrises and sunsets that this country offers. So please don't just speed thru thinking there is nothing there, you will miss some awesome country and people. OK done venting enjoy your rv'ing.LOL