This is our bathroom. We opened up the ceiling to expose the roofline, added skylights. Also did the same in the hall bath, with similar result, other than the fact it was a very small bath that we were able to steal 18" from the landing to help enlarge it. Other than having only one real place for each fixture, it wasn't a problem. Shower and tub worked well in both baths, but the lowest height of the ceiling I think is 72".

Here is a link that might be useful: Where my photos live