Both of those like like they will work fine. You have good sight lines in both, nice size and shape of spaces, etc.
I wouldn't worry too much about the modal issue: Everest also says that for rooms that are only slightly non-rectangular (such as yours) you can estimate the modal behavior by averaging the dimensions. Besides, modes can also be attenuated with suitable treatment, and a recent study I read on hundreds of high-end control rooms around the world implies that many of them do have modal issues, to one degree or another. So don't get too hung up over "golden" ratios and "perfect" modal spread: Even if they are spread perfectly, they still need damping!
I'm becoming haunted by acoustics...day and night!
He he he!! Welcome to the club! You are now fully qualified to design and build your studio.....
Stuart, I know you had said a notch like that wouldn't be an issue as long as the front was symmetrical. Any change of heart in that regard?
Perfect symmetry all around is great if you can get it, but the most critical part of the room is the front half. That's where the first reflections are happening, where your ears are, and where the speakers are. Further back is where major absorption and secondary reflections should be going on, with those also being directed into absorption, or diffusion. The concept is to have only a direct sound field in front of you, and develop only a diffuse sound field behind you. If it can be evenly diffuse, then great. If not, then aim to attenuate it as much as possible. Your offset at the rear won't make it 100% "evenly diffuse", due to the lack of symmetry but is sure does look like you plan to kill the entire back end with major, deep absorption: From the shape, I'm guessing that you are thinking of hangers and superchunks back there? Good choice. You have enough space, so that should work well. In fact, you might even be over-doing the absorption back there! That's not just killing a few lows a bit: that's a downright murderous massacre of the entire spectrum going on back there!!!
Now, if you are REALLY concerned about the rear end of the room, and would love to make it "perfect", then just slide the bathroom over a couple of feet, and continue that left wall all the way back at the same angle: It should end up more or less where the toilet is at present, so you'd have to slide the bathroom over by maybe 2 feet.
And if you really wanted to be even more perfect, you could angle the entire rear wall to be parallel to the front wall, or maybe just angle the left half, but either way making the room totally symmetrical again. (That would open up a small triangular space behind the control room, which you could maybe use for a strangely shaped closet in the bathroom...)
Also do you think the CR in layout 13 could sound better than layout 12 since it upholds a true 20ms RFZ? Or am I splitting hairs?
They way you have that laid out and what I'm assuming is deep bass treatment on the rear wall, should give you excellent RFZ. That rear end looks like it will be very dead, and you'll probably have to tune that to not kill the highs too much, but it certainly looks like you are ticking all the right boxes.
However, having said that: 20ms for the Haas effect is only an average estimate for the general population of humans on this planet. For some people, 20ms is just fine, for others as little as 10ms might be good, while still others would still not be getting it at 30ms. So yes, shooting for a perfect 20ms is maybe splitting hairs a little. If it was 19 or 18 it would probably still be good, and I've seen some recommendations saying that a "15/15" criteria is still acceptable for studios, for most people (15dB down, and 15ms late). So this is like ratios: there's no such thing as "perfect", so just get it as good as you can.
Ahhhhhhhh so many compromises every which way. I really like certain aspects of both designs.
OK, that settles it! You are most definitely qualified now! You have passed the final test for home studio design, and you'll be receiving your decoder ring and instructions on the secret hand-shake by mail next week.... !
Seriously, I think it's time to stop sweating these things too much, and start fleshing out your model now, so you get yourself even more confused as you take things into 3D, and start designing your treatment, HVAC, electrical, door seals, etc....
- Stuart -
(speaking of designs here 
). I have some questions regarding the bathroom walls, however I don't see much need to get into it right now since I haven't begun the 3D for this layout. It's mainly an issue of what to connect the RC to in that space where there is no framing behind the back left wall of the CR. 
