When towing the MPG we never go over 60 mph, so always adjust Google estimates upward. The whole reason for visiting Yellowstone and the Tetons is to enjoy the magnificent scenery. We've been several times before, as tent campers, but it's been a few decades since the last visit, so we're really looking forward to this trip. We're both originally from the West and began visiting this area as kids. That was way back when bears were allowed to roam freely around campgrounds, before the big earthquake and way before the big burn in the 80s. Most traffic jams were because tourists stopped everywhere there was a bear, so we know to expect lots of stopping and starting as we navigate through both parks, though bears are likely to be unseen.
Thanks again for the helpful info!