Trick to really cover the ground is to turn the motorway drudgery into something interesting/exciting in itself. This means either really pushing the speed for a day's riding (sit at 100mph for 9 hours and only stop for fuel, nothing else), or better, doing a very long day in one hit to get the lion's share out of the way.
The alternative (which I generally prefer) is to take twice as long and go via the backroads and really explore. If you have a road-based sat nav that you can set to "avoid motorways" and "shortest route", you can find some really neat places, yet still ultimately be travelling towards your destination.
I like my bike because I can overtake 4x4s down farm tracks with a week's worth of shopping on the back.