Of course, the first step was to do some internet research. I found an article at The Fun Times Guide to Household Tips, in which Lynette muses about size, style, and material, and prompts comments about color and other considerations.
Having decided that the toilet seat task and the article merited a post, I went to Flickr to find a suitable photo. I did not give serious consideration to using a photo of the incumbent seat (or of an incumbent on that seat). My thanks to Mark Blevis and his opthalmologist.