I dabbled in creating map styles like ten years ago, with Mapnik and TileMill. For our local cycling community I made a style that looks excellent printed in black&white, on which we could overlay routes. It was called like the community: "Veloroad".
Trained eye could notice multiple things on it that even modern styles don't do: look at road and river names, station symbols, place visibility.
There is a working tile server, but super slow. Probably gonna take it down.
Obviously running command-line tools to produce a map is not ideal for non-GIS people. So I also made a web UI to prepare route maps.
You just upload a GPX trace, adjust the printing bounds, add a scale bar if needed, and download a PDF. Another online tool would merge several PDFs into a booklet.
It's actually a set of tools underneath, some fix mapnik's SVG issues, some preprocess the values. I know of at least one business spawned from this (not mine obviously).