I had heard that Marley dies in the end, but I didn't know how "graphic" it was until I read this post. If you have ever had the horrible experience of having to make that decision, it can haunt you for awhile...even though it is the right thing to do. We lost my bullmastiff in September of 2007, and it is still too soon as far as I'm concerned for a movie like this.
I'm with whoever said they prefer uplifting movies, and I really hate it when they advertise a movie as a comedy and slip something like this in...The Family Stone comes to mind.