Is there a point when a room is too big for an exhaust fan? I'm not really sure I need one. Our new bath will be very large, about 192 square feet, but it is really a series of smaller rooms (dressing area, bathing area, toilet area, etc) open to one another including a 4 x 7 foot shower "room" with a window. The rest of the space has two additional windows and a pair of french doors that open to the deck. None of the separate areas have doors except the shower.

When I looked at one brand's calculator they didn't even have a unit sized for a space as large as what I will have.

I am not interested in putting an exhaust inside of the shower because I know it will never be turned on for fear of taking away all of the warm steamy heat. In our previous house I never turned on the fan for the exact same reasons. Our bathroom there was not as big, maybe 12 x 9 and the mirrors never even fogged up and we never had moisture problems or mold. In our rental house which is much much smaller I open the window over the shower/tub once it steams up. Nothing beats standing in a steamy shower sticking your face out the window when it's snowing!

Would I be better served to just put a small unit over the toilet? The shower walls and ceiling will be tiled if that makes a difference. The floors everywhere will be tile and the walls partially tiled. Or should I put one in the shower and turn it on after we've showered?