A long run of cable use a heavy 10 AWG wire..to be safe. With shorter runs at 2ohm load I would say you could go with a 12AWG or even a 14 and be safe...my opinion only and sure many will think different.
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Assuming you want the cable to be as neutral as possible, the basic ideas are that:
1)You want to limit the resistance of the cables carrying low frequencies to a small fraction of the impedance of the speaker at low frequencies.
2)For the cables carrying high frequencies you want to keep the combined effects of resistance and inductance to a small fraction of the impedance of the speaker at high frequencies (cable inductance may be a significant factor at high frequencies, but will not be significant at low frequencies).
Resistance and inductance are both directly proportional to length.
You can calculate resistance from a wire gauge table such as this one. For a 1 to 3 ohm speaker impedance at low frequencies, I would try to keep the cable resistance in the area of 0.05 ohms or less. That would be the resistance of the cable length x 2, reflecting the total length of both conductors.
For a 1 to 3 ohm speaker impedance at high frequencies, I would also try to keep the cable resistance roughly in the area of 0.05 ohms or less. I would try to keep its inductive reactance (the impedance caused by its inductance) roughly in the area of 0.25 ohms or less at 20kHz, as calculated by the formula 6.28 x 20,000Hz x L, where L is inductance in Henries (for the combined inductance of both conductors in the cable, which is sometimes referred to as the "loop inductance").