Triple post. Sorry.
I just read over your posts again and I didn't address (which is pretty much all I should have addressed) your point about great range = great actor.
This is where things great real subjective. Does Natalie Portman have great range? Good not great, but give it time, she's like what... 28?
I don't even know if Linney even has great range. I'll have to dwell on that. She's still a fantastic actor.
I'll have to dwell on great modern actors and get back to you. Tom Hanks definitley has range that not deniable but whether its great is really subjective.
I actually don't think Pacino has great range, but it's also not deniable that he's a great actor.
To use your example:
To me, what makes a great actor is someone who is able to stretch yourself from your usual role. DeNiro can play a psycho in Taxidriver, a young Vito Corleone in Godfather II, Jake Lamotta in Raging Bull, and even be funny as hell in Midnight Run.
I could say Brad Pitt has great range. Don't laugh yet. He's done pychotic, method and funny. Obviously not as well as De Niro but still a similar range? That does not put him in the same league as De Niro.