I have been to all of these places by train though I visited Görlitz on a separate trip (from Dresden). I walked across the pedestrian bridge to Zglorzelec just to have a Polish meal. But the Zglorzelec is much less prosperous than the German side, at least the part right on the border. I had only a night and didn't get too far into Zglorzelec, which I suspect has more charm further away from the border. But Görlitz on the German side is a lovely town.
You might be disappointed looking for scenes from "The Grand Budapest Hotel" in Görlitz however. You can find them - I found a few, but although it was kind of cool, it was mostly just a shrug. Don't go because of that.
I think the trains between Krakow and Wroclaw have been improved since I was there in 2012. You should be able to get direct trains place to place, easily. I don't care for long-distance buses (which can be cheap and just as fast, sometimes faster than the trains), but if they work for you and you don't love trains as much as I do, buses might be OK too.
Be sure to see the Racławice Panorama in Wroclaw - a circular painting depicting a famous (and rare) Polish military victory over Russia in the 18th century. I guess this isn't the first or only circular painting in history (maybe it used to be a "thing?", but I found it really unique and interesting. There is a museum in Wroclaw mostly devoted just to this painting.