school_backyard and dust_iplay have massive, oversized blocks.
When picking what maps to stay and what maps to be sent to the chopping block I looked at if it would have enough material for 16-24 players (8-12 humans, due to unbalanced teams sometimes), the size of the blocks (you would end up being a zombie enterring in a seemingly endless base that would not be replicable without the block size being so big) and if the material wasn't hidden away, as in, easily accessible and enough of most varieties of blocks.
I've purposefully left the majority of the classic basebuilder maps (such as ultrabuild, basement, corners, crete), even though for them it barely makes it as enough material, but, they are the classic basebuilder maps.
As for other maps, I've listed the requirements to be met for maps to be added (note: there were maps added further down the line without my approval but when players complain they never think to mention the maps in question).
So, just keep in mind, no oversized blocks, don't think "oh how long i can make the base this way", think from the zombies' perspective too.