We cruise at 58-60 MPH in our E450 24 foot Class C and it feels just right:
1. No engine noise.
2. Enough time for the DW to observe and identify wildlife.
3. Probably at least 10 MPG mileage from the V10.
4. Fast enough to be beyond a mysterious rattling noise we've had for 10 years when traveling around 40MPH.
5. Slow enough to stop quickly and safely.
6. Slow enough so any small side-push from a big rig doesn't bother us.
7. Slow enough so unexpected side-wind gusts on the open road in New Mexico don't put us into an unsafe situation.
8. Slow enough so the dog doesn't get motion sickness.
9. Slow enough to fully enjoy the music.
10. Slow enough to suddenly and safely steer around or slow up so idi*t drivers coming at us from an oncoming lane don't cream us head-on when trying to unsafely pass a vehicle.
;)