A couple of different secondary stylesheets?

If you have a theme options page, it should be easy to just add a dropdown and if it has a value load the stylesheet in header.php

I am not at my usual place so cannot give an example until later, but I am testing it here, home, page and singular.

I will post something later tonight.

David

For the options page this might help, read the comments as there is a small issue, download the sample theme as the code below is based on it but not tested!

The Stylesheets
Create a folder in the theme called /styles/ and add in your alternate stylesheets.

These can only change fonts, colors and graphics not the layout, give them a friendly lowercase names like crimson.css, purple.css, blue.css, colbolt.css.

NOTE: Based on a childtheme and using STYLESHEETPATH change to TEMPLATEPATH if not creating a Child Theme.

In the theme-options.php.php add a function to get the stylesheet names and a variable.

// Get the Stylesheets
function sa_list_styles(){
	$path = STYLESHEETPATH .'/styles/';
    $list = array();
    $dir_handle = @opendir($path) or die("Unable to open $path");
    while($file = readdir($dir_handle)){
        if($file == "." || $file == ".."){continue;}
        $filename = explode(".",$file);
        $cnt = count($filename); $cnt--; $ext = $filename[$cnt];
		$name = $filename[0];
        if(strtolower($ext) == ('css') ) {
			$list[$name] = array( 'value' => $name, 'label' => $name );
		}
    }
    return $list;
}
$sa_css = sa_list_styles();
array_unshift($sa_css, "");

Add in the stylesheet options in the general section for switching stylesheets.

// Default options values
$sa_general = array(
	'default_css' => '',
	'footer_copyright' => '© ' . date('Y') . ' ' . get_bloginfo('name'),
	'intro_text' => '',
	'featured_cat' => '',
);

Then to display the option on the options page.

<tr valign="top"><th scope="row"><label for="default_css">Default Stylesheet</label></th>
<td>
<select id="default_css" name="sa_general[default_css]">
<?php
foreach ( $sa_css as $style ) :
	$label = $style['label'];
	$selected = '';
	if ( $style['value'] == $settings['default_css'] )
			$selected = 'selected="selected"';
		echo '<option style="padding-right: 10px;" value="' . esc_attr( $style['value'] ) . '" ' . $selected . '>' . $label . '</option>';
endforeach;
?>
</select>
</td>
</tr>

header.php

$settings = get_option( 'sa_general' );
if( isset( $settings['default_css']) && $settings['default_css'] ) {
	wp_register_style( 'customstyle', get_stylesheet_directory_uri() .'/styles/'.$settings['default_css'] .'.css', '', '0.1' );
	wp_enqueue_style( 'customstyle' );
}

That is about it!

David

Here is a working solution, details and a child theme download.

If this is enough to get you going towards a solution, mark the topic as resolved.

HTH

David