I'll throw a few of these out as I have a busy weekend and won't get a chance until next week.
This isn't following your color theme, but this is my favorite beach theme. Very soothing colors.
I always think of lanterns when I think of the beach. Would love a three grouping on a round table.
Love the top photo with the serving bowl filled with sand and shells. The bottom photo gives me the idea of a larger pail with shells, star fish, silver dollars and a beach ball. Of course, I don't know what sizes you will be able to find in a beach ball. Never looked around for that.
I like this. I can picture various sizes hanging over the buffet table. Of course, you could also hang beach balls mingled with a few little pails, shovels or maybe starfish you find at a party shop.
Ignore Timmy and Randy. You have to visualize the Margarita glasses being something else.

I love the glass serving dish with the white sand and the balls. You could make those with Styrofoam wrapped in fabric that is the colors of a beach ball, or scrapbook paper Mod Podged to stick and give a shine. I think crepe paper colors would bleed with glue, so that might not be an option.
Anyway, that's a few ideas. I'd throw some sand dollars or tiny shells in your vases with the sand if that is what you are wanting to use.