This paper addresses a spoken dialogue framework that helps users make decisions. Various decision criteria are involved when we select an alternative from a given set of alternatives. When adopting a spoken dialogue interface, users have little idea of the kinds of criteria that the system can handle. We thus consider a recommendation function that proactively presents information that the user would be interested in. We implemented a sightseeing guidance system with a recommendation function and conducted a user experiment. We provided an initial analysis of the framework in terms of the system prompt and users' behavior, as well as in terms of user's behavior and his/her knowledge.