I started noticing my back developing faster once I started paying more attention to strict technique. Now my general philosophy for back training is to use the most weight possible without sacrificing the best form. So in other words, say you're doing BB rows; whatever your form is using only the bar should be your form when you're using weight. A lot of people jack the weight up and then have to use a total body effort just to pull the weight. If you're trying to impress your boyfriends in the gym, it may work, but probably not. If you're trying to develop a quality back, it definitely won't get you very far. Of course on your really heavy sets a little bit of cheating is inevitable, but you should still keep it to a minimum.
Also, my upper back appears wider and fuller ever since I've started doing my pull-ups very, very strictly. I pull myself all the way up, then lower myself all the way down to a full stretch. The set ends once my form starts slipping. After any pulldown exercise, I'll usually grab hold of something and stretch out each side for like 10 seconds or so.
After my back workout is ended, I like hanging from a pull-up bar for as long as I can just to get a great stretch. You could take it once step further and hang using a weight belt. This stretching feels great after a workout.
The amount of taper you have greatly depends on your development, how lean you are, and your genetics. But a wide back and thicker shoulders definitely help achieve that look. And don't do any obliques exercises where you use weight, such as weighted side bends. The only thing you need for obliques is to add twisting movements to some of your abs exercises, really squeezing your obliques during the twist. Also, standing side twists with a light bar across your back really helps. My obliques are MUCH tighter now than they are in my avatar picture which was taken about 2 years ago.