So this is what I was thinking. Now, what would you build?
Here's a novel for you:
Take this with a grain of salt, as I haven't heard the SEOS. I have some 1 off homebrewed line arrays.
Limiting this to diysg speakers in your price range:
I would build fusion 15's over the 1099 for the front 3 due to its lower crossover frequency with the bigger waveguide and simplicity of a 2 way/2 speaker box, just like notnyt said. But, I have a projector and an acoustically transparent screen.
Do you have $ into a TV already that you want to use? I have less than $900 into a benq 1070w and a 130" diy fixed frame millliskin spandex screen, I can't see myself having a TV again.
The volt 10's seem like a great surround speaker.
Not much difference in what I said before, or your initial thoughts. 1099 would work better with a TV with the horizontal center only being about a foot tall so you can tuck it tight under the screen. But speakers should be vertical, if someone was using 3x 1099's with an AT screen they should all be vertical.
Going out of your budget, and mine. What would I WANT? A seos24/dual AE TD18H+ with the Apollo upgrade for the front 3 basically lukeamdman's build and the same speaker with a single 18 for surrounds. Or from diysg 3x 1899's and 4x fusion 15's.
Subs:
Out of budget:32x fi IB318 with each sub getting about 250W and no high pass.
In budget:
(DISCLAIMER-While lots of power on a couple voice coils seems to work fine for many people... I don't consider my listening habits average, YMMV, to each their own.

) Personally, I wouldn't go for the high power low speaker count subwoofer route. I listen to a lot of dubstep and like it LOUD: Skrillex, Bass Nectar, Excision, Knife Party, etc. A lot of the bass lines are like test tones that want to melt your subs. For this reason I have gone the opposite direction with lots of cheaper speakers with way less power per sub. Like 85W-150W per sub, not 1800W per.
I also chose class H amps that are inefficient compared to class D, heavy, and will churn out watts on a continual basis without shutting down (I haven't used an inuke). I chose multiple ep4000's 650Wx2 so I could spread the load across multiple amps on multiple circuits. 20A circuits provide 2400W continuous and the amps draw 1800W continuous without tripping their 15A internal breakers.
What would I do is easier to answer for the subs:
Here is the build I should have finished today. It is the same external dimensions as 2 full martys. 16x 1260W's cost me $863, nearly identical to the cost of 2 uxl's. I have another 16 of these subs waiting for boxes, and ultimately plan on having all 32 in MASSIVE ported boxes (400cuft net total) tuned to 9hz and getting about 85W-100W per driver. The sealed box is just for fun, comparison to the ported.
http://www.avsforum.com/forum/155-diy-speakers-subs/1917921-16-x-12-sealed-sub-cabinet.html
Here is a comparison of 16x sealed 12's blue, 16x ported 12's green, and 2x full marty with UXL18's red. All 3 with 3,600W (an inuke6000). The sealed and uxl have the same box size, the ported graph is 2x the box size of the uxl's both are tuned to 17hz.