For me there is a categorical difference between 24mm and 28mm. I think of 28mm as the widest lens I'd use where I don't want an exaggeratedly wide look, like for an environmental portrait in a particularly tight space.

24mm starts to have a "wide look," so I'm more likely to use it for big landscape subjects, or photographing tall buildings where I want to keep the camera level and crop out the excess foreground, or for interior architectural shots where I've got a lot to fit into the frame and can't step back far enough.