My house rule for bombardment is that the ships do not get an independent attack, but only boost the attack of one supported unit to 2. This works quite well in the Pacific game, and eliminates the ability of the US to simply wipe out the Japanese on an island by bombardment, as this simply did not happen. It also takes care of the problem off a naval force eliminating the opposition from a large area like France, Norway, Egypt, etc. by shore bombardment before landing any troops. I believe that this correctly puts the navy in the supporting role for the attack, and means that the major emphasis is the invading forces success. I also have a house rule that air attack cannot eliminate infantry units, but may eliminate artillery and tank units. This also works very well in the Pacific game, as it means that you cannot eliminate an opponent’s forces if they include infantry by simple air attack, especially on islands, but you have to use ground troops to take it. An air unit may support an ground unit in an attack on infantry units just like artillery, increasing its attack roll by one, but does not get an independent attack.
The reason for the difference in air attack on artillery and tanks is that those forces are more vulnerable to air attack, whereas dug-in infantry is a very difficult target. I am thinking about excluding Japanese artillery units on Pacific islands as well, as the Japanese in island defense primarily used their artillery in the direct support or direct fire role, firing from either cave or heavily protected positions. The aim is to achieve a closer relationship to what actually occured in the war without excessive complexity.