Hello and welcome to the board! This is only my 2nd post.
If they don't want to watch Star Trek, then there isn't much you can do.
With shows like Battlestar Galactica, Stargate Universe, True Blood, United States of Tara, and others my interest in Star Trek is waning.
Do they even enjoy other sci-fi shows? You like TNG so I'd go with Genesis, Timescape, or other episodes like that which are suspenseful. They may appeal to a more new viewer.