Personally, I like "village" style spawns, where each building/portal/area has it's own unique look but still ties together with your overall theme.(Of course, also decide what you'd like that theme to be... Hobbit houses? Medieval? Modern?) Also to me, gigantic builds just scream "I used a schematic", and though the builds themselves can be impressive...you want your server to stand out and not be run-of-the-mill. Keep your organization simple...constantly put yourself in the eyes of a brand new player. Can you find what you're looking for easily? Do things feel cramped or too spacious? Adjust accordingly and never forget the perspective of new players :)
If you're planning on creating a public server, I'd definitely suggest a plugin like WorldGuard which will protect your spawn and other important regions from being griefed.
Happy building!