Join Date: Dec 2010
Location: South West United States
I've found that unless you are pounding the slab all the time, average speed really hovers right around 50mph. That includes cruising at 65 ~ 70 (or as dictated by secondary highway conditions), with stops as needed for comfort, fun, food and gas. Add it all up, and (for me at least), the overall average speed can be considered to be right around 50.
So 300 miles is 6 hours of travel time using this formula. So if I were taking such a trip, and wanting to enjoy it, I personally would figure on (roughly) 300 mile days.
You could do more, for sure, and some days would be more, but I think to consistently go much farther in a day you'd have to be focused on the details of just covering ground, without much time / attention to smell the roses along the way.
So it depends a lot on what kind of trip you want to take.
'06 KLR650 - Well armored and filthy!
'11 DL650 - Dearly departed 8-12-17, RIP