What information should be shown on the charts are based on what the viewer wants. From your sample charts, the x axis indicates 'date'. For time serial analysis, people usually want to know the trending of the metrics and to predict the performance in the future.
Here are 2 suggestions:
- People may want to know how it will perform in the future. Add a trendline. Trendline could help people to predict the performance in the future.
http://onlinehelp.tableausoftware.com/current/pro/online/mac/en-us/trendlines.html
- People may want to know how far away from goal. When people mouseover on the points on the metric line, you can try to show how far from current metric to the goal.
Try to understand what information people want to know and visualise them. Hope my answer could help you.