I am happy with just 22 tiles. 9 tiles is not enough, especially given how much space DLCs such as parks life and industries take up, however, 22 is enough. I don't see why we have 22 unlockable tiles if only 9 can be used. There's not much point in having unlockable tiles if you can't use them all. Another problem is maximum vehicle numbers and maximum object numbers. With 22 tiles, I run out of potential objects. With 9 tiles, I started running out of maximum vehicles to the point where trains/trams/etc. were shortened, and even with a mod that quadruples them, I start to run out of vehicles at 22 tiles. I used to support private boats, but now I know that the game doesn't support enough vehicles at it, even with the quadruple max. vehicles mod at 9 tiles. Beyond 22 tiles, it becomes less of a city, and more of a megalopolis, which might great for some players, but not really necessary. Beyond 80 tiles, different tiles would need to start having different climates, which may be difficult. Having said, that, however, if there are more DLCs added which have assets that take up more space, then there may need to be more tiles than just 22, but it wouldn't be a significant problem unless there were something like more 8 or 9 new DLCs. With 22 tiles, I can't draw enough public transport lines to serve my city, as it exceeds the max number of objects. I'm not sure if this is a problem at 9 tiles, but it could for some players, I don't know