@thegreathoe:
my problem with doing that is that i have no control over what these guests might be doing… i cant penalize their vpn traffic or anything that they might be legitimately going to that shouldn't impact the network.
Most of the stuff uses known ports. Web on 80, secure web on 443… fairly complete list at http://www.iana.org/assignments/port-numbers
l2tp is on 1701, pptp is on 1723, isakmp is on 500 and so on (for vpn traffic examples).
So it should be quite possible to do a "give these things normal priority and downgrade everything else into the basement" type approach. Work intensive for you to first make a list of stuff you want to permit untouched and then implement the rules and it still won't be bulletproof if the torrenters run their clients on a known port, but might be better than nothing.