I think the key word is "comfortable". When I was 20, I took a 71 Triumph Trophy from Oil city, Pa. to Columbus,Ga. in one shot. It was about 895 miles. I don't remember it being comfortable. Going to the Ga. Rally from Tulsa, I went from here to Nashville. It was 623 miles. There wasn't one mile of that I would call comfortable, since it rained all the way and with all the rest stops it took about 11 hours. I have heard that an average safe time on a motorcycle is 6 hours. I think the key is lots of breaks and as little Interstate as possible. Enjoy the ride and scenery if possible.

"Catching a yellow jacket in your shirt at seventy miles per hour can double your vocabulary" Author unknown