My favorite secondary movement for bench is absolutely the floor press. More specifically floor press with chains. If I add chain weight instead of bar weight I can still feel more weight, but I can also do a few more sets and reps than if I added straight weight. Ryan Kennelly is hands down my favorite bench presser. I used to watch this dvd every day before bench. Most of my assistance work for bench has come from what he does in this dvd.
Minute 2:35
I have to attribute to this lift taking me from a 600lb bencher to a 750lb bencher.