I have a Canon 60D with the kit 18-135 lens. I am going to Bavaria and Austria in two months. At first I was looking at a Canon 10-22 for wider shots. However after further thought, I am now leaning to the Canon 28 1.8 for better low light capabilities. I want to spend ~$600 or less.
My believe is the 28 1.8 prime would give me sharper landscape pictures as well as better lowlight/indoor shots.