I'm not going to add the stairs to my Orchid, or my second San Fransiscan, and I didn't add the stairs to my Linfield. In my Apple Blossom, I wish I hadn't added them either. They made it hard to arrange the living room easily. In the San Fran that I built for my granddaughter, I put them in, but after she ripped them out, (she was only 2), there was a lot more room!
I guess it is a matter of taste, but from now on, unless there is a separate hall for them, or a very interesting set of stairs, I don't plan on adding them any more.