A good park road trip is not the one that draws the longest line. It protects hiking time, accounts for gateway traffic, and avoids turning every memorable place into a fuel stop.
Pace
Count usable days.
Arrival, departure, and long transfer days rarely behave like full park days. Name them honestly before adding another park.
Season
Let roads shape the route.
High passes, desert heat, snow, ferry schedules, and wildfire conditions can reverse the best direction.
Stops
Keep the places between.
Gateway towns, scenic byways, public lands, and cultural sites can make a shorter route much better.