First off this is an excellent thread.

Next, I think that everyone has made valid points. I'd like to add that weight lifting alone does NOT transform you into Mr. Adonis that you see gracing the cover of magazines. These people follow strict diets, take truckloads of supplements, and often get a little pharmacy help. Going to the gym for 30-60 mins 3 times a week will not produce that kind of physique. Almost everyone can benefit from resistance training.

On the other hand... why do you think that after 200 years the military still does basic calisthenics? Jumping jacks (side straddle hop), pushups, sit-ups, pull-ups flutter kicks, jogging and sprinting. Why doesn't the military have everyone in the gym trying to press 300 lbs? Because these are the basic exercises that help you to be a soldier (a survivor). They help you to carry your rucksack for miles, lift mortar rounds, jump in a trench and shoot.