Graz is a town, having still a city center with a lot of its original medieval flair. One of the best places to watch a sunset is on top of Schlossberg. There you may find Uhrturm (the clock tower). This landmark may be seen from most parts of the town. This is how it looks like:
The Horseshoe Bend is an incredible place to see a sunset. When you arrive at the right time, a front row “seat” may still be available. Though nowadays literally crowds are streaming to the canyon rim to see the Horseshoe Bend. But be aware of the steep drop right next to you! The 300m straight down are nothing for the faint at heart. And you sure wont want to drop anything as it would just be lost forever.
Now if you are careful and ensure that spectators wont ruin your shots, you may set up the camera quite close to the edge. I took my turn and created a HDR sequence (5 photos per frame) of the sun descending behind the horizon: