I don't claim to know anything, but I'm bored, and want to throw my opinion out there.
Tackles:
Pass tree: For LOT, Protector seems like the best SA out there in the pass tree( plus it conveniently tells you the 3 key skills necessary for playing the position, aside from strength). I'd neglect all other SA's in that tree at the expense of building Protector. For ROT (which I have), I would build the 1st 4 up equally.
Run tree: I consider the 1st 2 important for both LOT and ROT. With Hands worthless right now (or so I think it is) and Cut Block difficult to gauge, it's quite costly to build up Pancake...I'd just stick with the first 2 SAs in that tree.
Guards:
Pass tree: The only one I'm not crazy about is Shock Block, since it's effective against "weaker players" and most G's will be facing very strong DT's. I guess if have high confidence/stamina, you could neglect Absorb Pain.
Run tree: same as above.
I have no center, and thus don't even know what their SAs are. I'd assume Line General is pretty solid though