Duravit Open Space has a new solution that solves both problems -- space and containing the water. Their new corner shower enclosure is essentially two swinging glass doors that open to form a square shower enclosure. When not in use, they fold against the wall to give you more floor space.
The success of this design lies with the flush-with-the-floor shower base and the integration of the door, shower base, and fixtures on the wall. I think it's worth checking out. I'd make the adjacent floor the same color and/or material as the shower base for a more seamless look. LM