Interesting,... well if you're still undecided, these ideas would get work.
Two options that come to mind:
1) You could make two 5' x 5' growing carts (with canopy & floor) for keeping it entirely self-contained and movable. Although, you prolly have to make them 5' x 6' so you could have a place for reservoirs, carbon filter and fan.
But if you really want to go with built-in's, this is what comes to mind:
2) If we look at your plan view and say the top is North. On the East wall divide the length into three work bench like growing areas. Two areas for vegging under T-5's separated by a cloning area. The cloning area is centrally located to feed either veg beds.
Have the two bloom chambers side by side in SW corner of your plan view. The bloom chambers will create a hallway with the wall that the bathroom door is on. In this hallway are your two reservoirs for your bloom chambers easily accessible to the drain and fill capabilities of your bathroom. Pull high shelves above the reservoirs for nutrient storage. A workbench in this area is useful too, a horizontal surface to put your meters, measuring tools, scissors, journal and such. High on the south wall you want to suspend larger than you want ducting to connect the bloom rooms to the general area. It will be quieter. Also get a variac to tune the fan. As you walk in through the South door to your immediate left is where you put your carbon filter.
