Whether you are shopping or not, the Grand Canal Shoppes are a relaxing way to beat the heat as you stroll through. The faux sky on top and canal with singing gondoliers paddling through just set you at ease.
If you do want to shop, bring the ultra-Gold card because there are mostly high-end options from which to choose. Think Barney's of New York, Michael Kors, etc. There are plenty of restaurant options at various intervals throughout the Shoppes in case you get hungry.