<p>It depends on the time of year and location. In June, hostels will be fairly full in most places that are not out of the way. So I would advise making some reservations. Check out HostelingInternational and HostelWorld. </p>
<p>Also be aware that most hostels have single sex dorm rooms of various sizes, so they might need to find a spot than can accommodate each of them separately. If the want to get one room together, it will probably be designed for 4 people, but they might be able to take the whole thing (at a higher rate, of course). </p>