I travel at whatever the speed limit is. Since I usually travel 15,000-20,000 miles each year, in the decades I have been RVing I have seen the views on most highways and many of the secondary roads. My time on earth is limited and I would rather spend my time at my destination instead of behind the wheel of any vehicle. Saving a few pennies in gas is not a concern of mine. My Chevy HHR has been towed in excess of 50,000 miles with no damage from exceeding the 65 MPH limit placed by the GM lawyers.
Drive at whatever speed you feel comfortable at.