Generally, one round-trip Tokyo-Kyoto-Tokyo PLUS another trip such as the Narita Express to NRT, the Haruka express to KIX or a round-trip to/from Kyoto-Himeji will more than pencil out savings on the 7-day ordinary JR Rail Pass. Additional rail trips during the 7 days is just gravy. Longer trips make it even more worthwhile. The round trip from Kyoto to Hiroshima is also doable and makes the Pass extra valuable.

I always plan ahead by looking at my proposed rail trips on HyperDia to see what the cost would be without the Rail Pass before deciding to buy.

HyperDia | Timetable and Route Search in Japan.