The line that differentiates the dress codes for leisure and work has become increasingly blurred of late – for instance, pinstripe was once a signifier of the men’s suit for business; today it has become an integral component of the casual wardrobe.
Specifically casual suits have however become popular in fabrics like cotton and linen. Both are easy to wear and take colors well; the downside is that the material for these men’s suits is prone to getting creased easily, and that means linen and cotton are not normally used for more formal occasions – stick to traditional wool for those.
The all-purpose man’s suit in your wardrobe should be a dark two-button suit in black, charcoal or navy. It will be adaptable for just about any occasion; the type and color of shirt you wear and the accessories you put will ring the changes, trying a business suit (matched for instance with a white or blue shirt and a plain or patterned tie) into a less formal outfit (worn perhaps with an open-necked short in a strong color, or even a white t-shirt).