Max length of IC's? Long IC's vs short SW

Regarding your general questions, there is no universal answer. It is all highly dependent on the impedance characteristics of the specific components that are being connected, as well as the parameters of the particular cables. See this thread.

In the specific case you are asking about, unless your components or speakers have extremely unusual impedance characteristics it would seem very likely that taking 20 feet off of the speaker cable length, while adding less than 8 feet to the interconnect length, would be the preferable alternative.

Regards,
-- Al

I made a set of bi-wired cables for a client 75 feet long and he loved them.

Thanks for the advice. Any one know what's the max you can go with unbalanced IC's before you run into problems? Can I go 12 feet or should I try to do everything possible (unlikely) to get down to 9 feet? Thanks.

Most IC's have a spec for capacitance per foot. Longer IC's=more capacitance (generally means that the treble will be rolled off). Look for cabling that has low Capacitance per foot as far as IC's go.
Also, unbalanced cables are prone to picking up noise that you will be amplifying along with the signal from your source.
Speaker wires will have a much higher level signal moving through them, consequently a higher signal/noise ratio.