Some supply bases are worth grabbing, such as those with auto-reloader, improved shells, and veteran crewman/improved aircraft. Others, like the bomber strikes, are pretty useless.
Use the old Sibuyan Sea tactic - sneak a couple planes around the map edge and get their headquarters. You win the game by neutralizing the headquarters, so if you can manage to get them you'll win quickly.
For Spine the Japanese should forget about using BB's it takes to long to turn. All should spawn DD's, half of them Shimakaze on the island they do not have to turn at.
Rush the centre island. You will capture it before the Iowa's have got to the first supply base. Send your DD's on a torp suicide run when you have the airbase.
Then the half the team that did not pick Shimakaze should use Emily's or Ohka. When you've got the airbase use nothing but aircraft. They killed off the BB remember.
I like this game for the tatical standpoint, i usally bomb the crap out of the island with dive bombers and surface bombadment. Then launch a couple LST's or higgens while starfing the little soilders with fighters. Of course you could always just attack the island with ships and then use them to capture them. But thats boring.
island capture stratigies
Lets disscuss island capture stratigies