No Military press's are using your shoulders. (mostly front head of your deltoids)
Chins work all your back and the rear of your shoulders.
Paul
Or to put it another way - chins are the vertical pull, and militaries the vertical push. They are antagonist movements, think Newton's third law of motion "for every action there's an equal opposite reaction". The antagonist movement for the bench-press would be the row (bent over with a barbell for instance), these two movements are the horizontal push/pulls. A good basic routine would be the vertical & horizontal push/pulls, plus deadlifting (for hamstrings, back, grip etc) and squatting.
For instance:
Chins (vertical pull)
Overhead Press (vertical push)
Bench (horizontal push)
Bent over Row (horizontal pull)
Close stance back or front Squat (quad dominant)
Sumo Deadlift (hamstring/hip dominant)
As these are all compound movements, they'll hit your whole body, no need for pointless sit-ups or any other crap - your core is involved in all these movements as a stabilizer (especially in squatting and deadlifting, the 2 best core building exercises).
Things I would avoid are upright rows (bad for the rotator cuffs) - doing horizontal and vertical push movements on the same day (also stressful for the shoulders). Machines, avoid avoid avoid - stick to the free weights. Machines force your body into an unnatural path, you can get injured doing any kind of lifting but you're more likely to get injured using a machine. Also if you're doing squats or deadlifts - FORM FORM FORM!!! Read up on these exercises. The squat is especially difficult to master. It requires a lot of flexibility in the hips and hamstrings - dont let your lower back round as you drop down!