For me, a good landscape is the right combination of the location and the light. There have been numerous occasions I have taken photographs of certain places during bright sunny days which have come out "okay" as a record shot of that place but haven't conveyed any emotion.
Later in the day (or even very early in the morning) when the light is more acutely angled across the landscape (instead of being right overhead) - or even when it's chucking it down with rain, the scene can be transformed into something that makes me feel I've produced something more than just a straight record of the place.
Some years ago, I took some photos of a big refinery on Teesside. That was a seriously ugly place during the day but, with a low sun highlighting the pollution spewing forth from the chimneys, it looked beautiful - albeit still very toxic!