I like the small interaction between Scrooge and the maid, while he's hesitating to go into Fred's party. Barely a word spoken, but so touching.

Those are both terrific. The first shows the depth of his character even depriving himself of a penny's worth of bread. And the second: Marley and Scrooge sitting there super calm. I can see the director guiding them to play it very sedate. Because of that the scene
really
stands out for me. It's so different from just about every other scene Scrooge played with his emotions either angry or disgusted or whatever.
But my absolute favorite scene - in fact one of my favorite scenes in all moviedom - is when Scrooge wakes up on Christmas morning and is all giddy and frightens Mrs Dilber. They both play it perfectly. These two actors make magic together.