<div id='idthatiknow'>
    <div>
        <span>good1</span>
    </div>
    <div>
        <span>good2</span>
    </div>
    <p>
        <span>bad</span>
        <div>
            <span>bad</span>
        </div>
    </p>
<div>

$('#idthatiknow span').filter(function() {
    return $(this).closest('p').length === 0;
});

#idthatiknow > div span { /* your styles here */}
/* all spans with a direct child of div from #idthatiknow */


#idthatiknow span:not(#idthatiknow > div span) { /* your styles here */}
/* all spans except the ones with a direct child of div from #idthatiknow */