If limited to 3 only movements (and the time factor by the sound of your post) than consider the tried and true squat, BB row and bench press. If wanting something more out of the norm than than BB Hack squats, Dips and Up-right rows as the main exercises. The BB Hack squat will affect the total back as well as the legs very well. Think of it as a reversed DL, with the bar behind you rather than in front of you. You can let your imagination run wild as long as you include one compound exercise for the legs and a pushing (bench/incline press, dips, etc) and a pulling (rows, chins, etc) movement. Actually there are dozens of combo's that can give excellent gains.
If just wanting to keep in some kind of respectable shape, than any type of leg press, chest or back machine. Even the BowFlex can have an advantage for the average guy who just wants to settle for respectable shape.
As far as sets and reps go, 8X8's or even the simple 5X5. Or 6X8-10's, which many men prefer for BB'ing purposes. To the extreme, for a 6 to 8 week training cycle, than 10X10's by all means. But with the 10X10s, you would do lower body one workout and upper the next. Never lower and upper in the same workout. Very advanced work load for most people. Again, use your imagination to find what is best for you.
If wanting an excellent strength program than a Power Rack comes to mind. If no PR than standard power moves as cleans, pulls, push press, squat cleans. All these are good to build stamina (endurance + strength) if into athletics, mainly when higher reps are done (8-12). In any event you can become in top shape with these compound movements.
Assuming that you are aware of the diet you want to put into action with any program, than short and to the point workouts (3 movements) should fit you needs. Pretty simple stuff, really. Good Luck.
