In OnTime, we use the Priority and Severity fields to determine which defect needs to be worked on first for the next release.  Since we in support are not part of the development team, we mainly stick to the Severity field and let the project managers determine type of priority to assign for each item. This process helps us submit the necessary defects and let the development team determine how to prioritize their workload before they even start working on the defects. With this process in place, I can create a custom filter to only look at the values that I want such as Priority and Severity of each item. At the same time I can also apply a “Group By” setting in the application that will properly group each individual item based on a desired field such as priority or severity of the defect.

Hope this helps.