Your opinions on how to string 25 ft speaker cables

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.