I win a lot of smaller prizes from radio contests, but never any trips. However, I did win the grand prize cruise at Millionaire at MGM in 2004. Then in 2005, my DD got in the Hot Seat and was allowed to bring a parent to help her since she was under 10 years old. She asked for my help and went on to win the grand prize as well. If you go to the show and hear the floor manager mention the youngest person to win was an 8 year old girl, they are talking about her.
As for the current radio contest, I haven't heard any of our local stations participating but they could be. I've tried before to win one of those nationwide contests and never had any luck doing it. However, I have managed to at least get through a couple of times, I just wasn't the right caller, so I wouldn't say it is totally hopeless.
Rob