As a regular jumpseat occupant (aka commuter), I would say that 30% of crews will talk your head off, 40% will be polite and ask the typical "how's your airline doing" questions, and the other 30% will pretty much leave you to your newspaper. However, I've noticed that when I'm operating the flight, most jumpseaters will talk once spoken to and more often than not we will end up having some very interesting conversations. It is (as it should be) the operating flight crews' call as to whether it will be an enjoyable flight, or a boring one. Me, I'd rather make it an enjoyable one. Afterall, by about the 3rd leg of flying with someone I usually have them stereotyped and am bored.