the extreme values do not matter the most. It is important that the general pattern of your displacement makes sense. The mimimum and maximum displacement values often are produced by atmospheric influences or unwrapping errors.
As for your second example: Is it a coherent change that is expected? That means did the surfaces change their properties in any way (besides their elevation)?
I don’t know any of your study areas and cannot judge if the results make sense but your second example looks like there is a ramp in your data between the eastern and western part. It is always good to look at all steps of the processing. Does the interferogram look alright?