Airline employees and their immediate families can generally travel for free or a small fee on a standby basis. The fee for first class may be higher depending on the airline. The type of seat you get totally depends on what's available...you might get split up in coach, you might get to sit together, you might get first class, or you might not get on at all.

You can control this to some degree by planning to travel off-peak season. If I go overseas I go in Feb or early Nov, and I often will pick a destination based on availalability of first class (trip's a lot easir that way).