For a multi month cross US tour, I spend a lot of time looking at maps, possible routing, and things to see along the way. I start with a list of proposed stops with mileage etc computed. I like to compare my completed route, mileage estimate, and elapsed time estimate, with the end result. When it is all completed the original list is usually not very close to what I actually did, but it is a start. My last trip began with four plots on a US map. Three were locations of relatives that I wanted to see enroute, and the fourth was a good spot to cross the Mississippi River on a bicycle. Everything else just fell into place from there.