As a postscript to this, we're probably going for something travertine-related in 50x50. Any comments? Please feel free to express personal opinion!
A mirror is a consideration for the back of the room (running the length of the bath) but the constant demisting might prove tiresome (small children etc).
Here's the plan - but you're forgiven for not reading on...
Tiles would be full height on the back (shortest wall, which carries the length of the bath) and around the width of the bath at one end (for shower - at end of bath).
THen on wall opposite the bath end, they would run the full length of the wall about 1.3m in height.
The other short end of the room is a window.
The other long end of the room (minus the end of the bath) would have no tiling.
Floor is a wood Amtico.