I believe in the case of 9/11 that the official verison is mostly right. I have seen loose change and a few other documentaries on the subject and they make a lot of great points, but I would like to think that we wouldn't do that to our own people.
Though I feel that the government knew a little more then they let on and the way the building fell are very suspicious. I know a few people who think that the building fell that way because explosives were placed in the building after the attacks so they wouldn't fall at an angle and cause a lot more death.
This is coming from a 16 year old in the US.