Thinking about the scale of things

I remember going to the Tate Modern about eight or nine years ago to see the Rothko paintings. Previously I'd seen these only through the medium of books and thought they looked "interesting" and worth seeking out. I was not at all prepared for the size of the paintings and the huge emotional impact the paintings would have on me.
Someone recently commented that she'd like to see my work on a bigger scale and the Rothko experience resurfaced in my memory.
So recently I've been trying out some of my images
at different sizes to see how scale alters the impact and experience of an image. The biggest so far is about 60x90cm and the smallest 15x15cm.
Of course each image has the potential to be printed out at any size, but maybe each image has an optimum size that best suits the content and meaning.