In need of advice before I order an AE rack.

I agree with what maydonpoliris has written. There are a some further things I would suggest...

I would encourage you to get the system with blank panels/less modules first, even maybe just a 2 row system to get going. Then really learn what you need to have the system do what you want it to do. There will be a learning curve and more modules make it more daunting...    get the basic modules to make the noise, inc. dronx/drone 38, some sequencing, a filter or 2, and some modulation/CV/trigger generation.  The latter is a huge rabbit hole for the AE system...  The multifx would be a good unit for what you are trying to do, and the quantizer sensible if you feel tuning(s) may be a problem. Some of the modules you have specified I suspect you would not end up using a much as well, depending on you studio set up.

The 2 systems don't match completely - do you need a headphone out or not? There are other similar questions....

I would suggest having USB power from a main convertor and save your AE power supply, the main reason to have the AE USB out is the light...

Also note some modules you have put on are not currently available which may affect decisions. FMOS and Cirrus spring to mind. 

I would highly recommend the Solina module.

It looks to me like you haven't got enough CV/audio mixers for all the sources/destinations you are  thinking of  having, modules like 4ATTMIX/ 2ATTCV etc. These will be more useful (initially) than some of the processors you have put in, especially sine you are only showing 1 2VCA module.   I would add the 4VCA module as well.

The same applies with Envelopes, I only see 1 2ENV module on one system, the same on the other but the ADSR module as well. This still isn't a lot for the number of Oscillators/filters etc you are looking at getting, which leads back to my first point...

Whatever you decide, enjoy, 

instead of multiple FX modules you could go for one, and the STOMP IO. That way you could use any guitar pedal or outboard effect with your AE.

interesting that you should mention the Seq8 modes... there is no documentation of what they are or how to use ‘mode cv’ input , either in the TW shop or the wiki seq8 page.
pol ...  if you do get around to some wiki editing this weekend maybe that’s something to add? 
@maydonpolaris ..  do you have any more findings on that? ie: what level of cv hits random .. other modes.. pingpong, reverse??  i guess i should fire my ae up and figure it out for myself.

yep, i’ve just been upstairs doing exactly that!
2Att/CV to the rescue....   modes are ( for all those prospective SEQ8 purchasers ) .. 7 o’clock to 10 o’clock (aprox) FORWARD. 10 o’clock to 12 o’clock REVERSE. 12 o’clock to 2 o’clock PING-PONG. 2 o’clock to 5 o’clock RANDOM!!!!  
 can’t believe i hadn’t tried this yet... i’ve had a seq8 for more than a year...

The mode CV input had been left blank as I didn't know what it did? Thought I'd asked someone (as don't own the module) but no record of reply, admin could you update as you appear to have investigated? 

Pol.

Thanks for all the advice! I think I'm going to do a lot more research before I decide which modules to invest in at first.

Instead of a three-row system, I'd get the Monsta case. This way you'll have plenty of room to grow.

You'll need an extra 2VCA module and an extra 2Envelop module. You may want to get the ADSR, but I prefer AD envelopes. As you learn and grow, you'll find that certain modules just won't fit into what you're doing. New modules will come along that will fit perfectly. You'll need room for those.

Yep, can vouch for that one, have patch wires on nearly every order and still never seem to have enough!

First off thanks for the wisdom! The reason I was starting out big is because I know the sound I want and I have a year of patching the Neutron and 0-coast with the MPC and Keystep both independently and cross patching the semi-mods. I believe I have a good understanding of what they can and can't do for me. The "can't do" is why I want to go full modular. Considering all the advice (THANKS!) I think I came up with a solution that is an expanded stater system with doubles of some of the bread and butter modules with a 3rd tier that is dedicated to the drone.

Master I/O and HP amp
Bræd and Butter
2LFO x2
2VCA x2
2ENV x2
Noise
2ATT/CV
2S&H
Mixer 4-4, 4ATTMix, and DronX – mixers
MultiFX and Delay – FX
2OSCd and Wavetables – melodic voices
NYLE, Wasp, SV – filters
SEQ8 and rbss – sequencers, I also have the Keystep and/or MPC for sequencing.
TRIP – seems like it will be fun to do some wacky delay effects to a melody for rhythmic variations and accents.
MM-Div – for dividing MIDI clock in and triggering the SEQ8/other modules.
Wavefolder – adding flavor to the 2OSCd (or Noise, might not get this since I'm getting Wavetables, what do you think?)
Quantizer – to quantize melodies from the 2OSCd and Wavetables.
DRONE38 and Solina – drone textures and ambient chords

Ultimately, I want to tune the oscillators of the DRONE38 to different chords or notes in a specific key for the tonal low end and low-mid range. Set the Solina for midrange texture and ambient chords and have the Wavetables and 2OSCd for evolving melodies. The Drone38 and Solina will be mixed by the DRONX and the variations on the Drone38 chords will be done manually with the faders. The Solina chord changes may be triggered by an "individual out" of the SEQ8 or some other trigger for more randomness.
The Wavetables and 2OSCd will be triggered, SEQuenced, Quantized and effected (filters, envelopes, etc).

I can do drums with the MPC for now and add rhythm modules later if I want to.
Do I need the 4-4 Mix considering I have the 4ATTmix and the 2ATTcv (which will take over some attenuation duties if I'm using the 4ATTmix for mixing and attenuation) or should I keep the 4-4Mix and get rid of the 2ATTcv. I think there is overlap and not enough voices that will need all the mixing considering I can use the DRONX for the Solina. Anything I should add or drop (maybe drop TRIP, Wavefolder, and 4-4 Mix?)

THANKS again!

Hey! Yes I've watched most of your videos, some several times! Thank you so much for posting such informative content.

I know it'll be a pain in the @$$ but I'm willing to try and do what I can get the most out of the Drone38. It doesn't need to be exact tuning considering the overtones and all but I think it'll be worth the investment. I currently arrange drone chords using the neutron (2 oscillators and LFO to audio rate) with the additional 0-coast oscillator and it's slope generator to audio rate. This is a drone I set up and then play the synth voices on the MPC or my guitar over the drone; but that's only just one chord with evolving timbres and tones. I figure I can get the Æ set up in a similar but more satisfying way and have the modules kind of play it self while I manipulate the tones, faders, and sequencers to create evolving ambient music.

Thanks for all your help, the rack is ordered!