Where can I find a good, printable map (PDF) of Kraków (Poland)?
I find Google Maps not very suitable for a printable format. Being a road map, it's very much focussed on car travel and not so nice to read.
A quick Google search got me to Orange Smile's website with Krakow city guide. The map is pretty detailed and is in image form already so you can print it easily.
Since I've already been to Krakow, I can tell you that this map is quite adequate if you plan on visiting major attractions and explore the city center.
Very good map of Poland is a free UMP Map. It's something like Open Street Map, but in Poland UMP is usually more detailed than OSM. Here is Kraków on UMP. Just make a screenshot and print it.
There is also a commercial solution: map of Kraków made by Compass. It's a Polish company from Kraków, you can buy their map of Kraków in both paper and digital version (graphic file - PNG) which you can then print.
Inkatlas lets you create your own printable PDF maps in several styles (including for black in white printers). The maps are based on OSM and can include any GPS tracks or waypoints that you want to add. Smaller PDFs (6 pages or fewer) are free.
Full disclosure: this is my project.
Well, this vector map of Krakow is for a large size printing, but you can look if they have smaller versions: https://vectormap.info/product/full-krakow-poland-city-street-vector-map-editable-adobe-illustrator-royalty-free-printable-atlas/