Summer shoes should be unlined, for one thing, as that wears cooler. Unlined suede wears cooler than leather, which is why desert boots are not as willy as they may appear at first glance. But loafers are the most prevalent.
Avoid cordovan as the same water resistant properties that make it a good choice for rainy season limit its usefulness in hot weather. Same with boat shoes if you're not boating. They look good with sumemr clothes but they are not cool wearing.