Just came back from Cape Scott last night, found that Gaiters helped, but weren't essential (depending on the hiker). On the hike in I skipped them and didn't get dirty above my boots, while on the way out it rained and I wore them for the rain (along with shorts), and it made footing a bit easier. My feet stayed warm and dry the whole trip.

My hikers here are gore-tex high-tops, though my 8 year old mostly got away with low cut trailrunners (also gore-tex) and no gaiters. My 12 year old survived the trip in regular runners with good wool socks and liners, though in multi-day rain this isn't a good option. His feet got wet, and then dried out after a few hours of hiking when the rain let up. My spouse got gore-tex boots soaked in a swamp, and they didn't dry out even with the help of newspaper and the woodstove in the ranger's cabin.

I always carry crocs (the cheap dollar store variety, they are lighter) for beach shoes, you can go with sandals or anything else you want. Crocs are easy on in the middle of the night when you have to go pee, and great for washing dishes in the ocean, as they dry faster than fabric shoes.