You would have to offer both mani/pedi for someone to be interested, and if you are considering this I would only offer it if it is part of a GIRLFRIEND GETAWAY type package.
I am not sure how you can recoup the cost on it however, gas and time etc to get to your place.
Licensed and Insured is what everyone has mentioned, as I know nail salons have been sued due to improper cleaning of tools, and people getting a cut (which happens of course) and infection. So that is something to consider. If you yourself were doing them, that is another question. The third party part is the part that is not as easy to control. Example, if they booked this whole package and the person is ill and cannot be there. Then what? Sorry folks? You will end up eating the cost, you can't tell them oh well.
But I like the thinking of ideas to bring folks in and make their stay even better, well done.
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