Colleen, 1997 was weakish, but Good Will Hunting is an amazing film, and is totally better than Titanic.
I liked Good Will Hunting but didn't love it. And my point wasn't so much the quality of the particular movies as the "Oscar Best Picture-quality" of them. Most of the time a more intimate movie like GWH (or The Queen, or The Reader from more recent years) doesn't win.
The Best Picture is usually some combination of 1) history, 2) spectacle and 3) inspirational plus the "x-factor" of voters feeling obligated toward a particular person who hasn't won before, hasn't won in a long time, or was "robbed" in hindsight in a more deserving year. It's just the combo that the most voters seem to go for.
There are exceptions but there is certainly a Best Picture "type" that tends to win more often--Ghandi, The Last Emperor, the lavish 60s musicals, Titanic and Slumdog Millionaire all had that combo. I was actually very surprised that No Country For Old Men won because it didn't really have any of the three, and TWBB at least had the history on its side.
Sometimes I think the big sweeping ones win so often because so many people who vote in the Academy had some part in making them.