Ah, yes, east, west, left, right... I always get that wrong... 
Or as we used to say as kids: "Go left". Friend goes left. "No, no, I mean 'the other left'!"
In any case, you are right: pushing that city further east makes sense only if there is indeed flat land again on the other side of the hill range.
As to the 3SW site: an extra irrigation is not much effort, we'll need tons of workers anyway. An optimal city site for the rest of the game is a much more important factor. And having 2-3 additional coast tiles that can be worked for the rest of the game is a lot. Also consider: the sugar tile can be accessed from 4SW as well, so that wouldn't be a factor.
But in any case: all these locations are still question marks, we cannot decide them yet with the current information we have. For example, if a whale or fish becomes visible that can be accessed only from 4SW, then the decision becomes a no-brainer anyway...

Or as we used to say as kids: "Go left". Friend goes left. "No, no, I mean 'the other left'!"
In any case, you are right: pushing that city further east makes sense only if there is indeed flat land again on the other side of the hill range.
As to the 3SW site: an extra irrigation is not much effort, we'll need tons of workers anyway. An optimal city site for the rest of the game is a much more important factor. And having 2-3 additional coast tiles that can be worked for the rest of the game is a lot. Also consider: the sugar tile can be accessed from 4SW as well, so that wouldn't be a factor.
But in any case: all these locations are still question marks, we cannot decide them yet with the current information we have. For example, if a whale or fish becomes visible that can be accessed only from 4SW, then the decision becomes a no-brainer anyway...