I went to Miyajima on a day trip from Hiroshima. It is only a day thing and very easily accessed from Hiroshima. One word - GO.
MIYAJIMA has to be the most beautiful place in Japan. All I can say is, if you havent been, GO!
Climbing down from the mountain was just breathtaking. Beware of the territorial bees!! ^^
As soon as you exit the ferry terminal, you are greeted my Miyajima's most famous residents - DEER. I dont know why they pester the tourists for food and not the 'DEER FOOD' stall sellers, but hey, I guess that'll be too easy :)