I have brought my own floats. It's a lot easier to spot your kid when they're on a different colored tube or float. All those blue mats and clear rings look alike! And if you lose your float, it's easier to know it's yours when it's different.
My kids are too big for sand toys, so we didn't bring those.
We did bring snorkle gear for the kids and DH (he and I need prescription masks, but he had his from scuba certification, I was just blind!) The snorkle gear does take up quite a bit of room. For me, I'm not a real germ freak, so in the future, we'll probably only take DH's mask and just rent gear if we want to snorkle.