I like closed-toe Roman Sandals which protect your foot all-the-way-around, while still offering some "air conditioning" ventilation all the way around.  I wear these year-round (I live in Florida), and I hardly ever have occasion to wear socks anymore, unless I am going to church or to a business meeting or to a formal event, and then the dress shows have to come out of the closet.  The other 90% of the time... these are my shoes of choice.  I wore-out one pair (in 18 months), and so I recently purchased three more pairs of these... to "stockpile" for the future.  I've tried many other similar-looking sandals, but these are the most comfortable, by a wide margin.  Truly... the best Roman Sandals ever made.