For what it´s worth, I use the 24-70 f2.8L II and the 70-200 f2.8L IS II, combined with the Sigma 35mm f1.4 and the 85 f1.2L II for weddings and most other events. I occasionally use other lenses for church or fixed distant shooting, but 95-99% is shot with these four lenses. The primes I normally shoot wide open.
The 85 is probably the most challenging lens to use. No other lens produces the same 3D pop effect, with buttery bokeh. But no other lens can be as frustrating for its very shallow DOF. So if you go for that, it requires practice and more practice. But no other lens will be as rewarding when you learn how to use it. It is a slow focuser at close range, but from 3-4 meter (9-12 feet) I don´t find AF speed to be an issue. The challenge is to make sure you focus on the right thing.
The 135 f2 may have some qualities beyond what you get with the 70-200, but I have never felt that need. I have never used that lens myself, so it may be that I have missed something here.