I did not use any plumbers epoxy to hold the rockwork together except in one place. There is a small wedge in the front right bottom that actually holds the bigger rock from tilting down slightly. Since there is a turkey wing behind it, I was afraid it would nudge it opening and closing, so I connected the two rocks. Other than that, it is just a matter of having a good feel for how rocks go together and an extra set of eyes to give input.
I had huge rocks though, so feel free and use epoxy. It is fairly easy to undo with a screwdriver or small prying tool. It is nice to use even just as a little blob in the joint of a slightly unstable stack. It will really stablize the work.
The gorgonian on the right is a candelabra gorgonian (species ?? have too look it up) All of the gorgs especially the sea fans seem to like pretty decent flow. The sponges seem to like even more. As much as ou can give them. I did epoxy/super glue combo all of the stuff to the rocks. I didn't feel that the sand was a good foothold.
It was a balance of trying to create the right microclimate for each critter and still satisfy my overall vision. I kind of have the mentality that what is meant to be in my tank is meant to be, so I had to work with the rock that came. My only regret is that I don't have a bit more sand real estate out front, but that is my fault for not getting a bigger tank

There is actually quite a bit of sand around and behing the islands though so it would have been a good layout for a room divider tank.
P.S. Divemonster, your tank is awesome, so don't play the cheater card with me
