IT, the reason that I suggested that RG-59 would be plenty for any coax that you had to run is that it has losses low enough for even a run of several hundred feet and the slightly lower loss of the thicker RG-6 wouldn't be significant. Shielding against interference is a separate question and depends on the type of shielding used, not whether the coax is RG-6 or RG-59 type. Sometimes cable TV companies use inadequately shielded cable, but as this excellent
article by the guys at Blue Jeans explains, that has nothing to do with the size of the cable. Their
test of cables showed that some RG-59 cables had hum rejection better than some RG-6 cables, if the shielding was better.