Hi Nelson,
The 14 day pass is ¥16800 more expensive than the 7 day pass so you'll need to spend at least that on extra tickets and passes to make opting for the 14 day pass a better option.
The kanto + kansai wide passes come to ¥15,000, and so you have a difference of ¥1800 between your two options of 14 day JRPass vs 7 day JRPass + regional passes.
For reference, here are some estimated JR ticket costs:
-
Tokyo > Maihama: ¥210 (15mins, 12km)
-
Maihama > Tokyo: ¥210 (16mins, 12km)
-
Tokyo > Yokohama: ¥1,460 (23mins, 28km)
-
Yokohama > Tokyo: ¥450 (27mins, 28km)
-
Tokyo > Otsuki: ¥2,860 (85mins, 87km)
-
Otsuki > Tokyo: ¥2,860 (76mins, 87km)
-
Tokyo > Nagoya: ¥10,780 (126mins, 366km)
-
Nagoya > Tokyo: ¥10,580 (106mins, 366km)
-
Tokyo > Tateyama: no route found
-
Tateyama > Tokyo: no route found
-
Tokyo > Osaka: ¥13,950 (194mins, 556km)
-
Osaka > Hiroshima: ¥10,150 (104mins, 345km)
-
Hiroshima > Osaka: ¥10,820 (109mins, 345km)
-
Osaka > Kobe(hyogo): ¥390 (24mins, 33km)
-
Kobe(hyogo) > Osaka: ¥390 (25mins, 33km)
-
Osaka > Kyoto: ¥540 (29mins, 42km)
-
Kyoto > Nara: ¥690 (44mins, 41km)
-
Nara > Kansai airport: ¥3,100 (76mins, 83km)
JR ticket cost: ¥69,440 for 16 legs
Looking at your list, I think it really depends on your travel plans and timings. Both Nagoya and Hiroshima are long distance trips and are only covered by the JR Pass so you'd need to fit these legs into your JR Pass validity period. It is possible to fit both of these into a 7 day stretch, but it may be much more relaxing for you to space it out over 14 days.
In the end, I think I'd go for the 14 day JR Pass as it offers more flexibility, however it does depend on your travel plans - you will certainly save money with either option!
Hope this helps!