I've never done a trip this long, but I have to say I like your idea of traveling by land, especially by bicycle. I'm reminded of "Zen and the Art of Motorcycle Maintenance" and his commentary of "being in the scene" instead of "watching it on the TV that is a car window" (paraphrasing here).

Also going by land is cheaper, and lower impact for those who care about that. It does cut your options, requires more time, and at least in America there's an awful lot of nothing in between even the non-touristy places.

I hiked the Haute Route (Switzerland and France) with my father and his friends in 2019, and while it was only two weeks, it was such a wonderful experience.