@fjarrett  I tried this previously, and just tested it again.  For some reason, this is the message I get.  It's the same as I was getting previously with $wpdb->prepare();

    WordPress database error: [You have an error in your SQL syntax; check the manual that 
    corresponds to your MySQL server version for the right syntax to use near 
    ''wp_stream' GROUP BY 'author'' at line 1]
    SELECT 'author' FROM 'wp_stream' GROUP BY 'author'