Any suggestions on good subwoofer interconnects?

I've had good results with Better Cables on long runs

I would look for used or demo models of Tara Labs RSC Prime Generation 2 or RSC Reference Generation 2. They're great subwoofer interconnects and come up fairly often here on Audiogon and sometimes even on ebay. I love them in my system. Bill

You might also look into the Anaylsis Plus Sub Oval interconnect which is quite reasonably priced.

IMO when long RCA cable runs are required, its best to go with a coaxal digital cable. IMO it seems to carry the signal better on long runs.