I'd go one step further and if you do RAGBRAI get cycling sandals with SPD clips. Alas, the best sandal (original Shimano) is no longer available but there are still some pretty good ones out there. The sandal option is great in a hot Iowa summer for both on and off the bike.
Some bikers laugh at the sandals, but I really like mine. Are they as efficient as top of the line bike shoes? Of course not, but I am not a top of the line biker either. Really great for hot days, or those days you get caught in the rain. On RAGBRAI I just step right in those big tubs of water sandals and all. They are always dry in 5 minutes.