Incidentally, a Guayabera is basically a nice elegant cool wearing shirt, that has about 4 pockets, and you don't tuck in. They are definately made for the TROPICS. I don't see why they don't take hold here in the USA during the summer.
I noticed when I worked for CONTINENTAL MICRONESIA years ago, they had an interesting dress code for buisness first that included the option of wearing those HAWAIIAN style shirts with buttons and collars, in place of suits and ties. It's just more feasable in the tropics to wear that style of clothing. Almost like a GUAYABERA but with the ISLAND look. Another great place for a GUAYABERA is in the PHILIPPINES as in most of Latin America. I've seen everyone wear them from office workers to waiters to buisness men. It's an all purpose elegant on the spot wear. I'll see if I can post you a pic here.