I was JUST finishing rebuilding my new base, but I'm okay with a new world if we have to, I would however like to keep my inventory and get a few basic things back that I'll be losing from the world.
I would also like to suggest 3 things:
1. Disable seeing people on dynamap or disable dynamap. Because people can see where everyone else is and anyone wanting to cause trouble knows where to target. Makes it impossible to hide your base if people can see you in it on the dynamap.
2. Minimal Spawn. I'm not saying don't put anything at spawn, but a simple lit room to land in or a path leading to the nearby town would be good, keep the load down for one of the most oft-travelled places on the map so that people don't have lag trouble where not needed. If they want to settle in a town then they can go and do that, but please don't build it on the spawn area again, it certainly caused problems for me
3. Try out the seed "Minecraftia". It's one I've been using for a while and has a very nice layout and variety of biomes close at hand. Even if you decide not to use it in the end, give it a look.