Attending mass in Poland (dress code and more)

I'm going to Poland (Krakow to be exact) in a month or so, and I wanted, while I'm there, to attend Mass. I would appreciate any recommendations on what church I should attend. Also, what's the dress code (I was planning on wearing dress slacks)? Any hints would be appreciated!

Smart casual. Some wear suits

Don't forget it will be cold and you might have to dress accordingly.

your sunday's best... for sure.. pick a church, any church.. they are all old and cool. :) then the following sunday pick a different one.. you probably ought to start on Wawel and work from there.

2 churches on Rynek are very cool too.. even if you don't go to mass, go and check them out.. the artwork is awe inspiring.

Krakow has some of the most beautiful churches. Many are open to the public - though some charge a small fee to go inside...its well worth it though to see the inside of them.

I also loved how the the priests and nuns actually dressed in the more traditional getup of their orders. Where I am its getting harder and harder to tell who is of the clergy and who isn't.