Graphic Primary Navigation and Text Based Sub Nav

I have been diligently searching the web, reading the Codex and trying plugins to no avail. I have accomplished this goal in Modx builds (ref: https://www.rutherfordncedc.com), but for some reason I cannot wrap my head around this in WordPress.

My goal is to have different graphic buttons for each primary navigation channel, and text-based subnavigation (Children) that only shows under the primary channel (Parent).

I LOVE the new menus control panel in 3.0 and would prefer to accomplish my goal using organic code as opposed to a plugin or hack. Can anyone help?

Reference link for current build.

WP install 3.0

TIA
Rat