Went on an Iberian interrailing trip with Euroventure last year with my boyfriend and they took the stress out of organising the tickets and passes myself. It worked out that we would have ended up spending nearly twice as much if we'd done it ourselves, cos it turned out we were looking at the wrong passes for our specific route! We stayed in hostel dorms as we were more bothered about seeing the sights than where we stayed, but even the hostels they picked ended up being really nice. We met loads of other travellers and even keep in touch with a few of them still! I'm already looking at booking with them again next year, and might even be brave and go for the 80 day route!