Business and the office
The best choice is usually dark-brown derbies or black Oxfords, depending on where you work. In more formal industries black is neutral, while in settings built on relationships and daily meetings brown looks less stiff. If you only have one pair, make it black, because it will also work with a charcoal or black suit if one joins your wardrobe later.
Weddings and family celebrations
A navy suit is one of the surest choices here, but the shoes should match the importance of the event. At an evening celebration in an elegant venue, black smooth-leather shoes look the most classic. At a daytime reception, outdoors or in a more relaxed style, dark brown works very well, especially when the accessories are in a warmer palette: the belt, the pocket square, a tie in burgundy or brown.
Dinner after work, a date, a restaurant
Here a navy suit does not have to look official. Dark-brown shoes with a more interesting detail, or even loafers, clearly change the character of the outfit. If you are going straight from the office, simply switching to less formal shoes makes the same suit look more relaxed.
An important presentation or job interview
When you want the most professional impression possible, choose black shoes in a simple shape. The shoes should not take centre stage; they should show that you have the details under control. Condition matters more than price: dusty or dull leather spoils the effect even in the best pair.