I'd certainly be game for another server but under my current circumstances I can't join a server, but yeah there are a few nicer mods to add but vanilla is the most simple way. Also vanilla is getting pretty fleshed out now. I would recommend some community spawn but everyone are free to build a base away from spawn if they want, no griefing, and no pvp except in places deliberately designed for pvp if anyone is game, I don't know many simple mods that are just good for community servers.
As for sky block worlds I would start of with a simple survival world if the number of player grows and it becomes large scale maybe you can increase it to cater to different interests.