After reading the various threads on hot tubs, my tentative conclusion with an upcoming listing is to NOT make it available upon special request (and with an accompanying fee). In addition to the various hassles, we have water restrictions that would make it prohibitive to constantly drain & refill. Fortunately, I'm able to lock both the gate and the hot tub cover, making it easy to "turn off" the feature.
However, I'm tempted to try and brainstorm creative ways to make the hot tub an inclusive (non-special request) feature, but am curious if anyone has a sense of how much more they earn or how more often they book because of their hot tub. Obviously, this is a difficult question to answer, and I'm sure is location dependent (a ski chalet in Vail probably fetches more than a summer rental in Louisiana). That said, does anyone have a sense of whether they make "significantly more," etc?