The Chūgoku (中国) region is rich with echoes of samurai life and castle ruins, temples less trafficked by the tourist hordes, and evocative sites from the Edo and Meiji eras.
The name "Chūgoku" literally means "Middle Country", the sole surviving relic of a historical division of Japan into "Near Countries" (近国 Kingoku), "Middle Countries" and "Far Countries" (遠国 Ongoku), based on distance from the capital Kyoto.
Modern-day Chūgoku is divided into two halves: the busy, industrial San'yō (山陽) along the Seto Inland Sea, with Okayama, Hiroshima, and Yamaguchi prefectures; and the quieter, less populated San'in (山陰), with Shimane and Tottori prefectures, facing the Sea of Japan. If you're visiting in winter, expect much colder weather in San'in, which translates roughly as "the shady side of the mountains".
You'll find fairly good English ability throughout the San'yō area, which is well-accustomed to foreign tourism and commerce, but San'in may prove more of a test for your communication skills.
The two major JR lines are named for the aforementioned San'yō and San'in areas. The San'in Main Line originates in Kyoto, and terminates in Shimonoseki. The San'yō Main Line goes one step further to Kitakyushu.
The San'yō Shinkansen, naturally, runs parallel to the the San'yō Main Line. Hikari trains from Tokyo will require a transfer at Shin-Osaka, but Nozomi trains will head straight through, terminating at Hakata on Kyushu.
The Japan Rail Pass  is a natural fit for travel here, as elsewhere in Japan. But if you're planning to spend a significant amount of time in this region, the JR West San'yo Area Pass  allows essentially unlimited travel in Chūgoku, Kansai, and part of Kyushu, including the Shinkansen (even Nozomi trains). The 4-day/8-day pass is ¥20,000/30,000.
There are several airports in the region, notably in Hiroshima and Okayama, with a handful of international flights to cities in Asia and connections to Tokyo. There's also a major international ferry port in Shimonoseki.