packing for a day in Chichen Itza
The pyramid itself and the location are not particularly colorful, but provide the excellent neutral background for you to wear anything bright and bold. My inspiration came from the stalls of brightly-colored skulls, plates and carpets.
Although traditionally people wear white with a red sash, I went for bright orange and pink tones (you'll stand out in a sea of white), and stripes or geometrical patterns go nicely with the symmetry of the structure.
It's hot (I went on March 21st) and there will be a lot of walking around and waiting around on the floor, so I don't recommend short skirt. Shorts, pants or a maxi dress are suitable. Flat soled sandals are highly recommended. You should also bring a relatively big tote for water and snacks (as the site is huge, but food and drink are only available at the door) and a towel and bikini - as you can (and most likely will want to) jump into the Cenote - a cool pool of clear water in a ceiling-less cave.