When RV traveling we found it most comfortable to spend 8-10 hours campsite to campsite, moving 100-300 miles a day. All sightseeing is done enroute, except major destinations where we might stay in one place 3-4 days.
RV or not, spending the whole day driving is tiring. Spending the same amount of time having fun, or stopping to rest, is not so tiring.
We had broad enough interests that we could always find interesting stops enroute, particularly if we stay off the Interstate highways which intentionally bypassed all the interesting small towns (they were supposed to avoid big cities too, but Ike lost that battle). There are trips we would make several times a year, for thirty years, and we could still find new interesting places to stop along the way.
Try a change of pace. The journey is the adventure.