I believe the travel benefits extend to your spouse (or domestic partner, or designated guest), your parents, and your children. You can give guest passes to anyone, but they're on a lower priority than your normal benefits would be.
IIRC, using the travel benefits doesn't cost you anything in the US, but guest passes and positive space passes do result in a payroll deduction for tax purposes, which I think works out to somewhere around 5-10% of the value of the ticket.