Here are some ideas of itinerary based on how many days you are planning to stay in Poland. The number of days and eventual orders of the cites are our suggestion.
The image below shows the order that we would recommend the visit, starting from Katowice.
The other assumption is that Katowice has 1 day for the wedding and over to visit/relax.
The number of days is based on our experience as we have visited all the places we recommend.
You could always spend different amounts of time, chose a different order, or even not wish to visit a certain city.