What casual men's shoes to wear besides boat shoes(sneakers excluded)?
Some form of suede/calf chukkas. Most things with a vibram off-white sole, practically anything with a crepe sole (desert boots, wallabees, etc). Some kinds of slippers (even velvet, formal dress slippers can look great when dressed down IMO, but /flamesuit on)
supercasual (not really MC at all) but currently in vogue (unfortunately for my eyes): Espadrilles