I liked IDOL, but I'm always frustrated by the Hollywood rounds because they're just TOO abbreviated. We have decent singers, and we want to hear them sing. And we only hear a small, small sample of those who go through.
The producers are very canny, however, in continuing certain stories from the audition rounds: the kid whose parents didn't support him, the Navy guy, the Indian brother and sister, the best friends, etc. Some of them make it and some of them don't, but the do get you wrapped up in following their stories.
Of course, for the ones that make it, they've had these two or three very special sequences to be featured while others that make it are barely seen at all. I've always felt those people start with a disadvantage once the public starts voting.