If you were fitting out your bathroom would you fit an extract fan
connected to a humidity sensor?

The bathroom has a large window.

I guess it's nice when you step out the shower to have it humid but
say 5-20 mins after a shower it's not so nice to goto the loo when the
bathroom is wet.

Perhaps a fan would work slowly so its still humid as you get out the
shower but after 5-20 min the place is de-himidiified?

Would a de-humidifier be more cost effective than a fan after all I
guess I have to heat the air that replaces the stuff that gets blown
out....