I try to keep things like this simple.
In my lightest load condition do I find myself trying to upshift to a taller gear to go faster, if so gear larger in the front or smaller in the back to correct.
In my heaviest loaded condition do I run out of gears going up hills? Will I see higher/steeper hills this coming year? Smaller in the front or larger in the back.
Think about your next tour and your last tour. Where will your heart take you and what would you change about your last trip?
Best of luck.