Ответ 1
Найденные столбцы сетки: http://getbootstrap.com/css/#grid-nesting
Пример: http://bootply.com/79487
HTML
<div class="container">
<div class="row">
<div class="col-sm-6">
<div class="panel panel-success">
<div class="panel-heading">
<h3 class="panel-title">Graph</h3>
</div>
<div class="panel-body">
<img src="http://dummyimage.com/600x500/000/fff&text=Graph" class="img-responsive">
</div>
</div>
</div>
<div class="col-sm-6">
<div class="row">
<div class="col-sm-12">
<div class="panel panel-primary">
<div class="panel-heading">
<h3 class="panel-title">Panel title</h3>
</div>
<div class="panel-body">
Panel content
</div>
</div>
</div>
<div class="col-sm-12">
<div class="panel panel-success">
<div class="panel-heading">
<h3 class="panel-title">Panel title</h3>
</div>
<div class="panel-body">
Panel content
</div>
</div>
</div>
</div>
</div>
</div>
</div>
update я забыл часть автохвота для примера выше, который вы могли бы использовать из fooobar.com/info/260057/...:
$( window ).load(function() {
boxes = $('.col-sm-6');
maxHeight = Math.max.apply(
Math, boxes.map(function() {
return $(this).height();
}).get());
boxes.height(maxHeight);
$('.col-sm-12 .panel').height(maxHeight/2-22);//22 = 20 (bottom-margin) + 2 *1 (border)
});