I've searched through thousands of seeds and wanted to find the exact same thing. In my experience you will almost always spawn near the bottom of the map unless there is not a suitable landmass in that area. Although I have had many spawns being underwater that were closer to being at the top of the map but none near enough to the center as I would like.
549229710. Was playing on mobile and spawned ad 0 0... not sure why or if i did something but pretty sure i found the seed that spans at 0 0 0. Again, this is on mobile and may change in future updates... playing on 1.1.3