Your opinions on how to string 25 ft speaker cables

I am running them through a hole in floor to crawl space, then up through floor to speakers. There are four cables to each speaker (Bi-wired)B&W 604s2 plus a subwoofer, Vandersteen 2WQ, (2 cables) nearby. Using 12 AWG two strand 99.9 copper nothing special cable from Monoprice. Should they be twisted around each other, or run separately and far apart, or in some other magical configuration for best of the best of the best, sound?

Wow, this is so strange, I have the identical situation. No, really, Identical!
You should have no problems. Although, if its an old house, I would be concerned about rats, and other rodents. To be safe, you can get some small diameter PVC pipe for the section of cable that is going under the floor. 

Also, since its a fairly long run, I would opt for a better quality cable. Audioquest makes some really nice speaker cable on a spool. It's not expensive and they sell it a Best Buy.
best sound is likely if you shorten the speaker cables as much as possible by putting the amps nearby

run long balanced interconnects using balanced components

even better; all distance should be covered in the digital domain using CAT 5e or 6 or WiFi, with a DAC and amp nearby

Thank you for your thoughts so far. However no one has answered the question. I am using the cables I have mentioned. I do not have rats, the question is, given the conditions I outlined, is it better to run them spiral around each other or separated from each other or some other way. Don't change my length don't change type of cable, just discuss the geometry of the cable run. Thanks 
Twisted !!! Twisting reduces inductance of the cable and shields the cable from external electric and electromagnetic interference (preventing induced noise entry back to the amp). It is because both wires are exposed evenly to external fields. Twisting might increase capacitance but it is secondary issue with speaker cables (low source and load impedance).

Light twist (1" pitch) should be enough, while it won't increase capacitance too much.  Use drill, to obtain even twist.

A slight twist may help keep them together and be a practical solution for installation. 

As as far as the sound goes - twisted or not - it is irrelevant for speaker cables.
I do not think there would be an audible difference at speaker level.  I do think that it will be easier for you to just pull the cables as a single bundle, rather than to twist them.  

I agree with Kijanki that twisting cables reduces emf effects and such, but you don't need to be too concerned about that at speaker level as the signal level is already so high. 

I work in the professional ,audio world and have been involved in many very high profile projects through the world.  I have never seen anyone twist individual speaker  wires, especially if carrying different signals together.

+1 richz.
If you should decied to twist don't forget that the wire length needs to be a bit longer.

I'm running a similar setup with similar cable, except with 2 less cables:  basically two 24' runs of 12 gauge AntiCables under the floor.  Speakers have only one set of binding posts, so this is just a true "double-run" of cable.  I went to the effort of trying this 4 different ways: cables run simply side-by-side in a "shotgun" type configuration (both conductors of one cable to the "+" terminals and both conductors of the other to the "-" terminals), cables run side-by-side in a typical bi-wire configuration ("+" conductor of both cables to the "+" terminal and "-" conductor of both cables connected to the "-" terminals), and then both of those configurations with the cables twisted together (one full twist about every 6").  Very obvious difference for the better (in this setup, and to my ears) with the bi-wire configuration -- the "shotgun" setup seemed to be a touch smoother on the top end, but robbed initial attack on transients and curtailed overall dynamics to a very noticeable degree.  The presentation got boring, if you will.  I did not notice much difference with either configuration in the twisted versus untwisted configuration.  As the twisted setup was my last trial, I just left them twisted and did not go back and untwist them for a final verification.  Happy enough with the result in that config. And the addition of the second set of cables was a very nice improvement overall -- more dynamics, more (apparent) extension in the bass, and more depth to the soundstage.

What 12 AWG cable do you have from Monoprice? Is it the clear or one of the CL rated ones that have a red and black in an outer jacket? IMHO, I would not use the clear in a crawl space.

12 gauge wire has about 340nH/ft inductance. It is 17uH for 2x25ft wire and represents impedance of 2.14 ohm at 20kHz. Bringing wires closer reduces inductance, twisting reduces it further.

As for high levels - levels for bass peaks will be in tens of volts, but levels for the soft tweeter sounds might be in milivolts. Any wire hanging is an antenna that feeds electrical noise into the amp. Speaker output post is an input for negative feedback while output impedance is low only for low frequencies.

Twisting pitch should be much smaller than the wavelength of the highest frequency we want to defeat. Wavelength of common 2.4GHz is 4.9".
1" twist pitch should be sufficient.
Thank you all for your thoughts. I will twist, and shout back at ya.

i am am using the white colored CL.