Forgot to mention that the “add-more” buttons don’t show up, either. Here’s a screen shot. The fields are always the same regardless of the selection.

@kevin, the flexible content configuration is working almost perfectly.

The “almost” is because for some reason when it displays the inputs for one of the repeatable options, it displays the wrong label.

Still, it’s close enough to show my client in the morning, and I know she’ll be pleased.

Here’s the full metabox file in case someone else would find it useful. I’m attaching an image that shows the label problem.

<?php
/*
Title: Flexible Panels
Post Type: post
Order: 90
Collapse: false
*/

piklist('field', array(
   'type' => 'group',
   'field' => 'flex_panels',
   'label' => 'Flexible Panels',
   'add_more' => true,
   'template' => 'field',

   'fields' => array(

      // first select the type of panel; this will determine which fields to add
      array(
         'type' => 'select',
         'field' => 'choose_panel',
         'label' => 'Choose panel type',
         'choices' => array(
            'grid_3' => 'Three-column grid',
            'columns_2' => 'Two columns',
            'boxed_rows' => 'Boxed rows',
            'wide_content' => 'Wide content',
            'looking_forward' => 'Looking forward',
         ),
         'value' => 'grid_3',
      ),

      // Headline field is in all panels
      array(
         'type' => 'text',
         'field' => 'headline',
         'label' => 'Headline',
         'columns' => 12,
      ),

      // Introduction field is in all but "Looking forward"
      array(
         'type' => 'editor',
         'field' => 'intro',
         'label' => 'Introduction',
         'columns' => 12,
         'options' => array (
            'media_buttons' => true,
            'teeny' => true,
         ),
         'conditions' => array(
            array(
               'field' => 'flex_panels:choose_panel',
               'value' => array( 'wide_content', 'grid_3', 'boxed_rows', 'columns_2' ),
            ),
         ),
      ),

      // "Looking forward" has a single Image field
      array(
         'type' => 'file',
         'field' => 'image',
         'label' => 'Image',
         'help' => 'Add or upload one image.',
         'options' => array(
            'modal_title' => 'Add Image',
            'button' => 'Add Image',
         ),
         'conditions' => array(
            array(
               'field' => 'flex_panels:choose_panel',
               'value' => array( 'looking_forward' ),
            ),
         ),
      ),

      // "Wide content" allows either two or three images
      array(
         'type' => 'file',
         'field' => 'images',
         'label' => 'Images',
         'help' => 'Add or upload 2 or 3 images, which will be displayed in a row.',
         'options' => array(
            'modal_title' => 'Add Image',
            'button' => 'Add Image',
         ),
         'conditions' => array(
            array(
               'field' => 'flex_panels:choose_panel',
               'value' => array( 'wide_content' ),
            ),
         ),
      ),

      // Main content field is in "Wide content" and "Looking forward"
      array(
         'type' => 'editor',
         'field' => 'content',
         'label' => 'Content',
         'columns' => 12,
         'options' => array (
            'media_buttons' => true,
            'teeny' => true,
         ),
         'conditions' => array(
            array(
               'field' => 'flex_panels:choose_panel',
               'value' => array( 'wide_content', 'looking_forward' ),
            ),
         ),
      ),

      // "looking forward" also has a bottom content area
      array(
         'type' => 'editor',
         'field' => 'content_bottom',
         'label' => 'Content bottom',
         'columns' => 12,
         'options' => array (
            'media_buttons' => false,
            'teeny' => true,
         ),
         'conditions' => array(
            array(
               'field' => 'flex_panels:choose_panel',
               'value' => array( 'looking_forward' ),
            ),
         ),
      ),

      // Boxes include headline, image and text
      // for "Boxed rows," each box is displayed horizontally on a full-width row;
      // for "3-column grid," the boxes are roughly square shaped and are displayed
      // three across. 
      array(
         'type' => 'group',
         'field' => 'boxes',
         'label' => 'Boxes',
         'help' => 'Enter content for as many boxes as you want. They will be displayed three across for 3-column grid, or one across for boxed rows.',
         'columns' => 12,
         'add_more' => true,
         'fields' => array(
            array(
               'type' => 'text',
               'field' => 'box_title',
               'label' => 'Box Title',
               'columns' => 12,
            ),
            array(
               'type' => 'file',
               'field' => 'box_image',
               'label' => 'Box Image',
               'description' => 'Add or upload one image.',
               'options' => array(
                  'modal_title' => 'Add Image',
                  'button' => 'Add Image',
               ),
            ),
            array(
               'type' => 'editor',
               'field' => 'box_body',
               'label' => 'Box Body',
               'columns' => 12,
               'options' => array (
                  'media_buttons' => false,
                  'teeny' => true,
               ),
            ),
         ),
         'conditions' => array(
            array(
               'field' => 'flex_panels:choose_panel',
               'value' => array( 'boxed_rows', 'grid_3' ),
            ),
         ),
      ),

      // Column content includes optional column title and body
      // Two columns exactly, please. 
      array(
         'type' => 'group',
         'field' => 'columns',
         'label' => 'Columns',
         'help' => 'Enter content for each of the two columns.',
         'columns' => 12,
         'add_more' => true,
         'fields' => array(
            array(
               'type' => 'text',
               'field' => 'column_title',
               'label' => 'Column Title',
               'columns' => 12,
            ),
            array(
               'type' => 'editor',
               'field' => 'column_body',
               'label' => 'Column Body',
               'columns' => 12,
               'options' => array (
                  'media_buttons' => false,
                  'teeny' => true,
               ),
            ),
         ),
         'conditions' => array(
            array(
               'field' => 'flex_panels:choose_panel',
               'value' => array( 'columns_2' ),
            ),
         ),
      ),
   ),
));