These need to be chosen specifically for each lifter; I think - again, just IMO - this falls into the domain of an experienced coach. When I am picking assistance exercises for myself, I generally go for the thing I like the least and look like a bumbling idiot while performing. Those criteria usually get me doing something that helps.When to include assistance exercises and in what manner. If your program minimum is deadlifts and bench press what would you program in and for what purposes.
Again, JMO.
-S-