A seat for sanitary equipment such as water closets and commodes, has an elongated aperture extending between the front and rear, two non-planar profiled areas bordering the sides of the aperture towards its front, and a relieved area bordering the aperture behind the two areas. The profiled areas are trough formations to receive and support the thighs, and the relieved area is U-shaped and dished around the aperture to clear the buttocks. In a commode, such a seat conveniently forms part of a platform including at least one supplementary seating area extending laterally from the seat, there preferably being two such areas to form wings in an overall configuration which is curved or angled in plan view. Other features associated with such a commode comprise a user support arrangement upstanding from the platform rear and including a back rest and hand rail/arm rests, and also legs with rollers which can be rendered effective or not, the legs and support arrangement being adjustable in height and, in the latter case, angular disposition.