We're staying in Oban for 2 nights and plan to visit the isles of Mull and Iona at least one of those days (most likely combining them into one day). Should we just do one of the bus tours that takes us to both? Or should we ferry over with our rented vehicle and explore on our own? Typically we'd prefer to take our own car and explore at our own pace, but not sure if it's practical for one day, plus I've heard the tours there are better than most. Opinions? Thanks!