Well, I'll chime in here two weeks after the fact....LOL
It's interesting how some people choose to do just a few exercises, with a large number of sets (reminds me of the bulgarians). Whereas others, might do a much larger amount of exercises, with much less sets per exercise. (Actually, I somewhat subscribe to both, in that I do very few exercses for lower body, with a higher volume per exercise, and for upper body I do more exercises, with only 1 or 2 sets for many of them.) Just pointing out an observation there - both work and neither is right or wrong.
Also, you noted that GMs seem to stress your hammies more than your erectors - here's what I'd do...Since you are doing the GMs relatively light, then keep a very close stance, bend your knees slightly, and push your butt back, AND ROUND YOUR BACK. Allow the weight in the bottom of the movement to really stretch your lower back. You don't have to worry about throwing a disc or anything - you've been doing this long enough to have a strong lower back, and hell, I've round-backed GMs well over 400 lbs past parallel with no ill effects.
Also, one question I had is why do you do the heavy close grip bench last on Saturday? Why not do it first - it will also warm up your pecs, and then move to the lighter decline dumbell work.
I agree with Freddy on the external rotations.
I do disagree on the dumbell rows. I find them entirely inferior to barbell rows, but that's just me.
I need to read over the periodization scheme Freddy mentioned again and post on it later - but I will say that I wouldn't go 12 weeks without a deload. Some guys can handle that if the loading period isn't too intense, but I've found that an 8 week cycle is better suited for the heavy loading, deloading period - with the heavy loading being in weeks 3-4, with week 5 normal, and weeks 6-8 a deload - but granted that's for strength-sport purposes. I figure with bodybuilding, you could run a 12 weeks cycle with a 5 week loading period (with weeks 4 and especially 5 being quite intense, followed by a delaod week on week 6. Then drop the reps and frequency down, and up the intensity for weeks 7-11, and deload again week 12. (Maybe even total rest on week 12.)
AM