For most players, Mazzi is the type of seed you immediately want to start with in Creative Mode. This particular seed offers a flat land for the player to build on. Of course, there are some bumps and divots throughout the land, but those can also be fixed with careful usage of materials.
Mazzi is perfect for sprawling cities. I, personally, use this seed when I want to undertake a massive project that I know will take time.
This seed can be used by inserting 'Mazzy' into the seed function in Minecraft.