How to choose a board?

Can anyone provide some guidance on what size board or boards I should find that my adult kids and I could use to learn how to surf? I am planning to set up my Pirata with both ballast and a wake shaper and want to find a couple of boards that could support 100 pounders and 200 pounders, and everything in between.

I'm a cheap bastard, so I tend to buy used toys. Should I be looking at Skim style? Board style? Hybrid? What sizes and shapes? Does it matter? The Wakesurf world is very confusing to me, I have no idea what's what.

Thanks!