Congrats on the "big boy" tank! Looks awesome.
Your question is like asking people who their favorite football team is. There are lots of good answers.
My experience suggests that the answer depends on the size, shape, and location of your rock work as it will impact how the water flows through your tank. Trial and Error becomes method needed to minimize dead spots.
My preference would be to start with aiming your 4 return nozzles parallel (but just below) the surface of the water and pointed at the tank face directly opposite. So perhaps something like the diagram below (view from the top looking down):
When viewed from the side, each of these return nozzles should create a rotational flow pattern together with the overflow that looks like this:
In this manner, you should get an effective circulation in the tank that (A) facilitates gas exchange at the surface, (B) sweeps detritus up from the bottom of the tank until it can be sucked into the overflow, and (C) avoid blowing directly on the sand and blowing it all over the place.
The wrinkle here is your rock structure which creates and obstacle forcing the water around and over it. Because your rock work is not symmetrical, that means you need to tweak the individual return nozzle position to try and enforce a flow pattern like what you see above, while not creating dead spots.
All of this get further complicated when you add powerheads to accelerate water flow. In my view, the best idea is to place the additional sources of water movement in locations that reinforce the natural water movement of your returns, while not going so far as creating strong uni-directional currents that exhaust your fish.
I'm not sure if I've helped or not ... but hopefully I've given you a starting point to experiment with!
