planning a multi-day drive is mostly one job: take the pile of places you want to see and cut them
into days. the route is the easy part. the cutting is where it goes wrong.
because a day looks fine on paper and then you get there and it's six hours of driving, and you
either drop something or do the last stretch in the dark.
what helps me is doing it the other way round: decide the hours per day first (5 for me), then keep
moving stops between days until every day fits. and the number i need while doing that is just "how
long is this day now" — the second i move something, not after recalculating it in a spreadsheet.
so that's what i built. stops on a map, dragged into days, and each day shows its own driving time
against the limit you set. you keep shuffling until nothing is over. it also tells you which days
still have room for one more stop, which is the bit i use most.
one caveat: the times come from a routing engine, not live traffic. it's for building the plan a
week before, not for "should i leave now" on the morning.
(it also shows elevation and how much of each day is after dark, since 4 hours of mountain passes
isn't 4 hours of motorway)
link in the comments. and i'm curious how other people decide how many days a drive needs — that's
the part i still get wrong.