I'd talk to your husband about the weather there, if he grew up there. If not, find out from his family what it'll likely be like over Labor Day weekend. If it's hot, here are my suggestions, and you can layer up to avoid the chill.
Ok. Casual...
clams or walking shorts
Jersey dresses, sun dresses, casual/flowy skirts, jean skirt
leggings (for under the dresses/skirts, like fathenry suggested. I wear leggings during the day too...it stops the chaffing when my thighs rub together )
jeans
cute sandals, flipflops (a YLF no-no, but they are casual), gladiators, or ballet flats...also converse
tunics (with leggings)
tank tops/tee shirts
I think you can look pulled-together even though you're in casual stuff. Hope that helped!