Other options:
Nuke an empty island
Nuke a military base
Nuke the whales
Wait. Maybe not that last one.
the japanese didn't surrender when we nuked a
city. those who focus on the
type of munition used often fail to place the amount of damage in the context of the war. WWII was killing a million people a month at this time; the A-Bombs weren't even the most damaging bombing runs over
Japan (more people died when we firebombed Tokyo).
heck, they didn't even surrender when we nuked
two cities. it wasn't until they became convinced (we bluffed) that we had another 100 Atom bombs, and would systematically turn every square inch of the Home Islands into ash that they had a vote -
and the vote was split! - the
Emperor had to intervene and break the tie.
and even
then parts of the military rebelled, siezed the emperor, and tried to quell the decision of the council (military control of the emperor having a fairly long history in the Japanese monarchy). if it hadn't been for the actions of a particularly brave palace servant stealing the recording of the Emperor announcing his decision, avoiding military patrols, and getting it to the radio station half an hour ahead of the troops, they could have very likely
succeeded; and then our bluff would have been called and we would have had to starve the Japanese Island to death before invading (Operation Olympic, the invasion of the Home Islands, was scheduled for November 1945).
remember, even
Okinawans committed mass suicide rather than face occupation.
and you think that somehow magically if we had nuked an
empty island that would have had a greater effect on them than one of their own cities?