Some of the local trails here are in the river bottom areas and get quite sandy. I'm not a fan of sandals all the time, so if I wear my trail shoes, I generally wear short gaiters with them. My thinking is that you cannot stop sand, but you can help reduce it.

Another idea... enjoy the sand and the surf and just go barefooted. Carry a light sandal/flip flop in case you need to run into town. Otherwise... enjoy the sand between your toes! How's that for lightweight?!?!