Great idea Angie, I will be following this thread with interest!
I think I am foot twins with Diana! I'm a size 7.5 with low volume feet and skinny ankles and slightly narrow in the sides but normal width forefoot and heel (I always look like I have a gap in the back when I wear pumps, even in the correct size for the length of my foot). I also have a long 2nd toe which tends to hang over the fronts of sandals. Because of my low volume feet and skinny ankles, I prefer shoes with an ankle strap to help keep them on. I also prefer more straps/coverage of the foot for thongs/sandals because I think they look somewhat long and scrawny when they're bare. But due to my low volume feet I don't really need a lot of arch support.
I am in love with Angie's suggested koi espadrilles, as I showed in my WIW post. Those are my favorite summer shoe now! I also bought a pair of Vans white sneakers because I wanted some white Keds, but these fit better on my low volume foot. (I also have Converse All Stars in red and yellow and a Tretorn Trey in Kate Spade Japanese floral and Vans sneakers in black/grey checkerboard). I loved the Ugg Izabel snake texture lace up pointy D'Orsay ballet flats so much I bought them in 3 different colors (black, blue and cream)! I also have the Sam Edelman studded gladiator sandals in black and silver. (These two styles aren't good if you need arch support though, obviously). I also have the heeled Sam Edelman Ollie studded black pumps and Okalas in pony, leopard, and red snake. My feet/ankles can be hard to fit, so when I find something that works I buy it in several colors, what can I say?
Birks don't work for me because of my low volume foot and long 2nd toe (it hits the raised rim), but I found a super comfy Birk alternative that works really well, the Munro Aries sandal. The stretchy straps really hold onto my duck feet. I also really love the Munro Abby sandal, super comfy all day shoe. They make it in other colors like yellow and red, which I tried but didn't love them as much as the black. I also have Worishofer granny sandals in gold metallic lace-up and red with an ankle strap. And some of my older sandals are black Topshop Jolie peep toe ankle booties (I still wear black a lot even in summer!), turquoise Tory Burch cap toe Pacey ballet flats, and Clarks Woodward Willows nude wedge sandals (my go-to with white flares and colorful summer tunics).
ETA: I guess I do have a bit of a shoe problem, don't I? Those Dansko Larissa sandals look tempting in tangerine...I think they would match my orange purse nicely!
