What costs more: adding on master bedrm suite or renovating interior walls, moving kitchen, adding bath?

From my experience, any time you start changing what is already in place, new and unforeseen expenses arise. Sometimes those walls hold unhappy little surprises. Are you basically happy with the size of the existing rooms and the configuration? If so, I think I would build the addition. It will be a little more straight forward. If not, invest the money in changing what you have. You will be happier in the long run.