Did you say you were adding 3 bedrooms and a bath upstairs? What is up there now?
I'm not sure about resale value, but i think when shopping for a home, the master bed with a bath was more appealing. I think i would pay extra for it, but if you have 3 bedrooms upstairs and only 1 bath up there, maybe it would be better to have it on its own instead of having it in the master bed. The thought of ppl in 2 other rooms running downstairs to use the restroom sucks!