Oh yeah, sand and mud definitely prefer different tyres.. I'd go for sand tyres.

I think the foreman would be an excellent choice, 4 wheel drive is great, but they are harder to steer , so I would get the power steering model. You may or may not need sand tires it really depends on the sand.

Hi. I'm in New Zealand and we have plenty of beach sand and some truly huge sand dunes here. In beach sand two wheel drive quads do just fine, even up the dunes that have drop-offs, and, as you suggest, the slightly lighter weight does allow them to skim over the top. In the dunes two wheel drive is nicer, lighter, more nimble and fun. I've also driven two wheeled bikes (XR hondas) though in mangroves, with mud up to your nuts, and I think you really would be better off with four wheel drive there. In the soft beach sand having four wheel drive is no disadvantage, they still go everywhere, but they feel heavy and do sink in slightly, but the four wheel drive hauls them through regardless. If you are going to be going into deep mud I'd recommend the four wheel drive, and yeah, hondas are excellent and the bike that's favored by our beach dwelling crowds.