I have mentioned this before...I do not seem to be built for such extended periods of riding. Today, I rode 275 miles from my camp to Old Forge, and back on the NYS Thruway. My butt was getting sore every hour or so, to the point where I could go on but wanted to stop, stretch, to keep the ride enjoyable. I was glad to pull in the garage at 6:00pm, after starting my riding day at 11:30am.
My first 100 miles - no problem - after that, I feel the need to stop every 50 miles or so (perhaps every 80 miles on Interstate travel). All I need is a five minute break and I am good to go again.
I know guys that ride around the country, and have 500-600 mile days; I am afraid to go with them because I will either drive them nuts stopping every hour or be miserable except for the first couple of hours or so.