My feelings are multiple. I do think speaker and interconnects matter more than the math about inductance, capacitance and resistance would lead us to believe.
I also think they are the least cost effective "tone controls" money can buy.
To get back to your question, longer cables should create more of whatever tonal effect they cause, but why? Your speaker choices and preamp are much better places to spend more money in finding the right combination of attributes you are looking for. Speaker cables are not IMHO a benefit, but rather a necessary evil for most of us who have passive speakers.
If you have monoblocks for instance, put them as close to the speaker as possible to shorten the speaker cables, at the expense of longer interconnects.