I want to add a master bedroom suite, would it be better to build out or up

The wall framing for a one & two story home r the same so theoretically ur house can handle it. Cost-wise there is going to be a substantial difference, I would guess maybe a 30-40% increase to build up. You will also have the issue of being limited by ur existing interior bearing walls. The interior walls on a ranch home were never meant to hold anything other than the roof so u will be limited in where u can build from. I would just ask a local architect or contractor to give u an estimate & discuss the options.

I am not an architect or a building contractor, but in my opinion, I think u have to consider the overall look & design of a house & take that into account.

Ranch-style homes r meant to be one-story. Common sense would indicate that they r not meant to have a second story, so how would they be able to withstand the weight? And, how would it look?

If it were me, I would add on the additional room & sacrifice the garden. For resale you're going to gain much more with a Master suite. Its far more desireable to have more living space than a garden. Few people garden anymore.

I am not sure of what the expense of either option would be, you'd have to have a contractor/achitect assist with that.

Thats a rather silly question for . Your house remodeling will be determined by the structure of your house. (We cant tell) Call a carpenter.