Good luck on your trip!
It is reasonable to figure 50 miles in one hour, average for a trip.
This includes fuel, food, and restroom stops.
How many hours is a personal choice, but when on vacation, trying to enjoy the trip as opposed to just getting there no matter the cost, 6-9 hours a day is a pleasant pace.
When we are taking a vacation to a far away place, I'll plan a couple days of hard travel to "get there quickly" (usually 600-700 miles a day) then slow way down so we can enjoy the new surroundings.
Rob
Waiting for "someday" will leave you on your deathbed wondering why you didn't just rearrange your priorities and enjoy the time you had, instead of waiting for a "better" time to come along...