Every once in a while you might be looking at the answers to a whole bunch of questions and notice a significant trend in the answers. This happens to me with diet - want to improve performance? Enhance longevity? Reduce inflammation? Reduce indicators of aging? Improve appearance? Moderate carbohydrate restriction shows up in research on all of these. So... eat fewer carbs!
I've been noticing a similar trend with training. Think about these questions:
Do you want to improve overall athletic prowess? Focus on training glutes and lats.
Burn fat? Glutes and lats (they're the biggest muscles in the body, hence will burn the most calories).
Increase overall muscle mass? Glutes and lats (see above).
Maximize your cardiovascular conditioning? Glutes and lats (see above again - bigger muscles means more cardiovascular demand means more fat burning means more potential for muscle growth).
Protect the spine from injury? Train glutes and lats (lats stabilize the core,supporting the spine; strong glutes protect the lower back).
Increase overall power generation and transmission? Glutes and lats again (hip extension for generating power; lats for stabilizing the core to transmit that power).
Look good to the opposite sex? Glutes and lats yet again. You can't beat a nice v-taper and a round, tight pair of cheeks to attract attention.
In summary, your training should always, always include a hip - extension dominant exercise (swings, deadlifts, squats) and some serious pulling (rows, pullups/chins, deadlifts, etc.)
You should also be doing some anti-rotation work, some pushing (pushups, handstand pushups,etc.) and some abduction/ adduction work, but everybody from the weekend warrior to the health conscious person to the serious athlete to the serious martial artist should focus their training on the lats and glutes if they want to see the best results.