If you do a lot of hiking on the beach then I'm sure you're aware of this fact- it's tough, tough hiking. You're either plowing and slipping through shifting, loose, dry sand or hammering your feet down on packed wet sand, which is like walking on concrete. I don't think I'd want to hike for any length of time without a well padded shoe. I've done it in sandals, with and without socks- mistake. I've done it with lots o' mesh trail runners- mistake.
I think for this type of hiking I'd resort to a well padded, comfortable tennis shoe. You don't need super lugged all terrain stealth rubber soles, so why even both with trail runners? I would probably even be tempted to toss some of those Dr. Scholls-type gel inserts in there. As for the send, well that's probably just inevitable. Gaiters might slow down the invasion but sooner or later, your shoes will be full of grit. I've often thought that if I were to do it again, I'd think about getting some Goretex socks and cutting them down to ankle height. Feet might get a little hot but- hey, you're at the beach!