Linen is one of the best materials for the summertime. It's fresh and comfortable, and specially popular around the Mediterranean (logically).
It can be elegant (for example a linen suit with shirt and tie), but at the same time can create a more casual and relaxed look (unbuttoned linen shirt, linen sport coat, etc)
Some good options:
-Linen suits (cream, Navy, light grey, black, etc)
-Linen sport coats
-Linen shirts (and linen & cotton shirts) in a wide range of colors.