If you want to build a massive server I sugest you make one that host's all, have it start out in an area where you must walk to a huge structure, be it a castle, or into a mountain. Then Have a room of portals that lead to the various servers. One that take you to survival mode, one that goes to creative, one that goest to hunger games/pvp area which can house multiple areas via warp signs so you have a hunger games arena, a normal pvp arena, the game arena for spleef i think it was called. One for skyblock, ect. That way everyone who like difrents game types will flock to the server.

But it's alot of work, and will cost money to keep it up.

I suggest you hire an entire building team so about 24 members total, and those who help build get a server status of some high rank, and the one who want to stay on for moderation will have better chances on that.

You will need GFX work as well for your server banner and server website, along with a reliable server host.

THose are just the basics I see in this journey.