I have a hwy leaving my town that is smooth as glass. It's also heading NW from the coast where there is always a SE wind from 12 to 20 mph. I have a town at 17.7 miles, 31.8 miles, 45.6 miles and 63 miles. Depending on time and how I feel, my favorite is the 31.8.
To make up for the tail wind and flatland, I ride at 90 cadence, 145 heart rate and varying speeds 17 to 25 mph. My wife is more than happy to pick me up on the other end if it gets late.