Columbia Falls to Bozeman

East on US 2 from Columbia Falls and south on US89 to Helena and US12 to Townsend to I-90 is 351 miles.

West side of Flathead Lake via 93 is 340 miles

East side of Flathead Lake via SR35 connecting to 93 south to I-90 just west of Missoula and then east to Bozeman is 323 miles

East side of Flathead Lake via SR83 along the Swan River to Condon and Seeley Lake to 200 to Ovando to SR141 to Avon to US12 to Garrison and I-90 east is 312 miles

Hard to say which way is most scenic - flip a coin. :) We've tried them all and they all have beauty to us.

IMO, Hwy 93 along the lake is the easiest, but Hwy 206 is prettier.
I grew up in Hungry Horse, and lived in Columbia Falls for a while. I can only stand to visit there for a few days now. The area has changed greatly, and not necessarily for the best.

You mentioned the routes around Flathead Lake. I've been wondering which is the most scenic and easiest to traverse for the MH, the east, Hwy 206N, or the west side, Hwy 93. We'll end up in Columbia Falls either way.

Other routes we have done from Columbia Falls are 83 south or 35 along the east side of Flathead Lake to 93 or even 93 along the west side of Flathead into Missoula and then I-90 to Butte and on to Bozeman. With your motorhome you won't have any problems with any of the given routes. Have a good trip!

Mowermech's route avoids the pass just east of Butte. There is long upgrade between Great Falls and Helena after leaving the Missouri River valley. In Great Falls there was a Dick's campground just east of I-15 that was OK. Either route is doable.

When I make that trip, I usually stay on Hwy 2 to Shelby, then take I-15 to Helena, then Hwy 287 to I-90 and then to Bozeman and Billings.
I like to use freeways whenever possible.
I have also been known to go to Kalispell, then take Hwy 93 to Missoula, then I-90 to Bozeman and Billings.
Nearly any combination of state, federal, and interstate highways can be done in a large RV.
Remember that if you have 4 or more vehicles trapped behind you, state law requires that you pull off where it is safe and allow them to go by.
Have a safe trip.

You will be fine .. Might hold up a little traffic headed up Marias Pass but there are pull outs for you to let traffic by. Once past East Glacier its downwind sailing.. No need to rush just keep speed in check ..the roads are good.