Theme modification for custom category menus

As indicated above, I discovered the answer to my own question. You do not need single quotes or brackets around the variable. The fact that the variable is a string itself is sufficient.

The correct code is below:

<?php   $cat = get_the_category();
                $catSlug = $cat[0]->slug;
                $catMenu = $catSlug . "-nav-menu";
                $options = array(
                            'container'=>'nav', 
                            'container_class'=>'menu-header',
                            'theme_location'=>'primary',
                            'menu'=>$catMenu
                            );

                wp_nav_menu($options); ?>

I’ve also discovered a multiple themes plugin located here: http://jonradio.com/plugins/jonradio-multiple-themes/

This would allow different themes for different categories. It may be overkill to create new themes just to keep the menus different, but if you’re looking for changing headers, menus, and layouts it may be what you’re looking for.