Trip Plan to Central Europe

For European timetables in general use the train planner of the Deutsche Bahn. The national railway companies give you the same timetables plus the price: the PKP for Poland, and the CD for the Czech Republic.
Could you put in Lódz between Torun and Krakow, if only for its immense and moving Jewish cemetery?
Kutna Hora and Cesky Krumlov are the tourist traps of Czechia. Try to get Olomouc as a stop between Krakow and Prague. Wonderful provincial town, still unspoiled by the masses. And instead of Cesky Krumlov you can have historical Tabor as a day trip from Prague (1,5 hrs on a more or less hourly train). Touristy, but in a nice way.

There is not currently a direct overnight from Torun to Krakow but you can connect to a night train before midnight. Saturday options are different and I wouldn't look more than two months ahead for these schedules. Daytime trains on the same route are as fast as 5 hours.

Thank you all for the information. tonfromleiden, I quickly browsed the 2 places you mentioned, Olomouc and Tabor. They are beautiful, and many people vote for these 2 places instead of Krumlov and Tunra Hora. Olomouc is actually not very touristy and worth to stay there for a night to experience the local life. I will go ahead to modify my trip plan accordingly. Thanks again.
Calvin

Those smaller provincial towns in Central Europe can be surprisingly attractive. When in Kraków resist the temptation to go to the salt mines and take the train (1 hr or so) to Tarnów.

Added:
There is no need to have an organised trip from Kraków to Auschwitz. There are reasonably frequent trains, taking around 2 hours, and it's only a 20 minutes walk from Oswiecim railway station to Birkenau (see this map). In my thinking a much more fitting way for visiting than being driven in a minivan: sometimes things shouldn't be done the easiest or most comfortable way.

Thanks again for your information. Your info is so detail, and I already started modifying my trip.
Calvin