As long as the visa is valid when you enter and leave you are okay. I think that what you get depends on what you send in and the mood of the person handling the request. I've heard stories both of people sending in requests for longer than their documentation being accepted with the requested dates and also of being accepted with only the documented dates.

I generally stay with friends and have used a visa service. I gave the service a longer set of dates than my intended travel dates. If you are relying on the hotel documentation for your visa support, why not reserve for a longer period of time and then change your reservation? You may even be able to express your concern about the visa directly to the hotel and ask them to extend the dates on the letter they send you.