I am currently running a copper backbone up my stairs into a cupboard, needing at least 5 prob 6 gigabit connections to it for my servers. Having to get creative with hiding the cat 5 under the carpet.
Huh? Put switches at both ends and just run one cable. Rather than going up the stairs you might consider co-opting the sewer pipe. Run the cable up that to your upstairs bathroom and out to whereever.