We present a novel approach to group recommender systems that better takes into account the social interaction in a group when formulating, discussing and negotiating the features of the item to be jointly selected. Our approach provides discussion support in a collaborative preference elicitation and negotiation process. Individual preferences are continuously aggregated and immediate feedback of the resulting recommendations is provided. We also support the last stage in the decision process when users collectively select the final item from the recommendation set. The prototype hotel recommender Hootle is developed following these concepts and tested in a user study. The results indicate a higher overall satisfaction with the system as well as a higher perceived recommendation quality when compared against a system version where no negotiation was possible. However, they also indicate that the negotiation-based approach may be more suitable for smaller groups, an aspect that will require further research.