I have a great solution! Try Easy Spirit Traveltime "sneaker mules." They're sneakers, but they're backless mules - very cute, extremely comfortable, come in lots of colors. I have them in four colors - due to a foot problem, I can't wear shoes that aren't "backless." Much cuter than a clunky athletic shoe when wearing capris and shorts. You can wear them with or without socks.
Check them out on Zappos.com. (Or, if you have a Macy's store near you, they often carry them, on sale!) Zappos is great - free (often overnight!) shipping, free return shipping if they don't work out.
(PS - just saw your second post about not having time to shoe-shop before your trip. Since you're not leaving until January 11th, order through Zappos - they often have free overnight shipping, and free return shipping, as I mentioned above.)