When creating multi-level lists you need to use different paragraph styles. This creates a problem where the spacing you want at the end of the whole list and the start of a new paragraph is applied when you are in the middle of different levels of the list.
I am thinking a little checkbox next to the 'Based on' paragraph style section in the 'General' tab of the paragraph style settings window that allows you to link the new style as a child of the top-level style.
This way, those end of paragraph spacings won't be applied to the child (or sub-level) styles...