I haven't seen it either. I have every intention of watching that one and the Green Mile too, but I'm hardly ever in the mood to watch that long of a movie. The Godfather is one of my favorite movies ever, but I haven't watched it in years for the same reason. 
Goodfellas was one I heard people talk about for years but I kept putting it off. When I finally watched it, I thought it was great. It had an amazing cast and was just really well written and acted. I've watched parts of it several times since, sometimes the whole movie.