The atomic bomb memorial is definitely an experience I'll never forget.
I found Hiroshima to be a good central place to stay for the area, I booked the Hotel Granvia Hiroshima attached to the station when I was there which gave me easy access to the shinkansen, JR, and Hiroden trams, and spent a few days going to surrounding areas such as Iwakuni and Miyajima to the west, the bomb memorial, Mazda factory tour, fooding in the city itself, take the ferry to Etajima for the naval academy and Cruiser Tone memorial, and a day trip to Kure for the Yamato and JMSDF museums.