You probably could have done this room with just one case, but since you bought two...
Use one case to build six four inch thick bass traps. Use four of them to treat floor to ceiling in the corners behind your monitors and two more in the back corners, but because of the odd nook and door put them in the wall/ceiling corner rather than the wall/wall corner. They would pretty much go wall to wall above the sofa.
Then take the other bale and make a dozen two-inch thick traps to control the slap echoes. Use them in a combination of behind the sofa on the back wall, at the first reflection points on the side walls and as clouds above the workspace.