Oh, and you can sell or gift a trip.
You mean you CAN'T sell or gift a trip, I think.
The thing about trips is this: on the surface, I would be excited to win a trip to somewhere nice! What an opportunity I wouldn't otherwise have....
...until I actually start to think about and plan the logistics of it.
Plinkoman is absolutely right (and he would know better than any of us!) A "free" trip isn't free by any means, unless you're fortunate enough to be retired and can afford all the fees, taxes, and spending money.
Make no mistake, if I won a trip somewhere, I would do anything in my power to take that trip and enjoy the experience. Realistically though, my life, work schedule, and financial situation would me it difficult, if not impossible, to take that dream trip - even if it were "free".