First of all: Thanks guys!
I was using vray for many years and i have to admit that i never reached a state of full satisfaction with the images. One reason was surely the very short termed projects but as an architect i never understood why one has to do so many workarounds to simulate the reality. In Corona it's completely different! You get what you have done before and that is a huge time saver.
The lighting in the scene is done with a sunny hdri and additional corona planes in front of every window to light up the scene a bit more. With other hdri's there were no planes needed but in the end i decided for that combination. As you can see in the image below, i didn't change the color much in ps (Upper left part is corrected). Just a bit colder as the hdri is quite warm.