You can do both if you plan it out. I did both carpet and stained concrete in mine. The stained concrete surrounds the bar, where the most spills occur. The carpet guys just used a nice brass edge strip to frame the stained concrete:
We also did the same stained concrete at the walkout/ back door entrance, and you can kinda see what it looks like in this pic, to the left of the Qbert:
I eventually will prolly tile the stained concrete. I wanna go with classic black and white checkerboard in granite or marble.