I have a suggestion. Money doesn't play that big of a role in play world, and implementing it now so late into the map might not work out. Maybe make that world based just on currency or something? LegendaryCraft has an amazing economy if you want an example.
Isn't Play world the only place money is used right now?
Actually I think I've seen a shop setup in Sky Zone as well but really it's just Play world.
Once you're able to purchase land, we may have a bit of a problem now that everyone is settled and I'm sure we'll have some people buying other peoples "already claimed" land which could be an issue.
I thought it would be good to have to separate worlds as well but even when I was adding people to the whitelist, people never played in there because they were by themselves... ?
Yeah. Multiple worlds = bad idea. I have played on servers where there is a set up where you place to dirt blocks and diagonal ends of your plot, and use a simple code and a stick to claim land. you couldnt claim others land, and it didnt include the sky or underground. Just everything between the dirt.