Hi John,
If I understand correctly, you would like to be able to insert single line breaks instead of "double" line breaks. In the visual editor, you do this by hitting Shift+Enter instead of Enter by itself. "Enter" creates a new paragraph, "Shift+Enter" just inserts a line break. For example:
Line 1 (hit "Enter")
Line 2
…as opposed to:
Line 1 (hit "Shift+Enter")
Line 2
Let me know if this addresses your problem.
Thank You!
Weston