Are you considering rearranging the rock to change the water flow or to create growth/life on the back/bottom of the rock?
If you answered to create growth/life on the rock where it is not currently happening- don't move a thing.
Similar to a natural reef in the ocean, sunlight is what causes the growth and proliferation of coral, algae, sponges etc.... Any part of liverock that is not exposed to lighting will not be cosmetically pleasing for some. On the other hand, as your tank matures you will be amazed at the appearance of many new items on the rock in the area you are questioning (sponges, tubeworms, beneficial bacteria....etc...) -
Keep in mind that many of the non-visual inhabitants of a reef do not neccessarily like sunlight and need these areas (bottom of live rock) to thrive.
If flow is your concern, are you using some type of external filtration? (trickle or wet dry filter with a sump)
If so check out the thread on seaSwirls in the equipment forum.
If you are using a closed system with the 3 powerheads as the only method of creating water movement, try placing one in the center of the tank pointed directly at the front glass with the other 2 in each corner facing directly forward also. This configuration creates a figure 8 pattern of water movement that in my opinion offers the least amount of dead space.
Best of luck,
Chris