A well-cut blue suit, crisp white shirt and some type of loafer (in brown) can create a look that is just dressy enough and just casual enough for almost any occasion.
I have tried the same look with a blue shirt but it loses the crisp contrast of navy/white and doesn’t create as much of a “finished” look.
A black suit/white shirt combination seems a little too formal and a bit cliche.
I keep the look interesting for myself by changing the model and fabric of the shirt – maybe a linen spread collar, maybe a cotton button-down, or maybe a mercerized cotton polo. I also like to change the shape and fabric of the pocket square but I avoid making my choice of pocket square a focus of conversation (that’s a whole separate post).