Memcache implementation
You should decide what exactly you need, before deciding those 3 options.

My suggestion is as following:


Install memcache and the necesary php module to use with memcache. Once you install memcache, you will have an IP and PORT to connect to, for SET / GET operations
Decide where exactly in your Wordpress php code you need to inject the code that displays the "featured" stuff
Add a php code similar to:


CONNECT to memcache
Check for the existance of a KEY/VALUE pair, named "FEATURED STUFF"
If there is, GET that pair, and display the pair's value
If not, run the SELECT query, FETCH the results, build a string that will contain the HTML body of "FEATURED STUFF", PUT the string in memcache as a KEY/VALUE pair.

The code above should not be cached with WP Super Cache. Let memcache do the cacheing for you.


If you need help with the actual implementation, let me know. 


Sample PHP Code:

$memcache = new Memcache;
$memcache-&gt;connect('localhost', 11211) or die ("Could not connect");

if ($gotten = $memcache-&gt;get('featured_stuff')) {
    echo 'CACHE HIT'&lt;/br&gt;';
    echo $gotten;
} else {
    # Never mind - fetch it and store for next time!
    $gotten = dbfetch($query, ...);
    $memcache-&gt;set($featured_stuff,$gotten);
    echo $gotten;
}