Oops, just noted that was the WitP forum, not AE... Well, some of may still be applicable to your problem?
I can think of many "interesting" moves, but most are kind of gambits and very few that really come down to a good force economy. It all also depends much on which scenario you play?
With scen 1, there is not a lot of options that are really feasible: likely just limited gains such as (one or a few of!) Darwin, Adamans, Ceylon and Diego Garcia, Aleuteans, Midway and Johnston Island, perhaps someof Nomuea, Fidji, Canton or Line Islands, but no large scale conquering of OZ, India, or Hawaiian islands. The latter seem to be doable if you are very quick with your initial "standard" objectives and can start the next phase early. A few rare IJN AARs come to mind that almost succeeded with large-scale efforts (FatR's attack on Hawaii, or the Cannorebel vs. Q-Ball match featuring India).
Most targets serve to create a buffer zone to the Allied forces, their long-range bombers, and gain space to trade later for time in the defensive phase. Adamans are a necessary flank security for both Burma and Sumatra, and provide good air bases and naval staging grounds for control over the Indian ocean. Also Aleutians are primarily of defensive value I would say.
Darwin is one place in OZ many IJ players try to grab early when it is still "cheap", since it is rather isolated by the dessert and not that easy to retake for the Allied player (air range being one issue, supply another). I can be held rather easily, and since it is hard to achieve a surprise attack against it, IJ can usually evacuate it in time without being trapped. Some people have taken East and West coast cities down to Perth and Brisbane I recall (see PzB vs. Andy Mac), just north of the reinforcement trigger line.
Nomuea, Canton, Fidji and Line Islands are key stations for interdicting the CONUSA-OZ or -NZ convoy routes and very good forward staging bases for raiders, LR-T-bombers and subs. Fidji and Line Islands have the benefit of several mutually supporting islands, but you need to have the forces and speed to take them. Later, they are rather exposed, but can still buy time and cause the Allied player headaches. I put those very high on my list, the benefits seem to be huge. However, you likely can't take both unless you are very lucky, so Line Islands may be first to try (you can recon Pearl and cover Johnson Island well from there). They are deep in Allied territory and close to Pearl, though, offering the Allied defender some advantages.
If playing scen 2, and being really quick, you may have a shot for the Hawaiian chain. Some players say, however, that IJ won't be strong enough in a game against a human opponent to take it, and even if you managed, the losses might be crippling. Not sure, haven't tried anything like that yet. One thing for certain, it will be a battle of attrition, but securing it (without crippling losses of planes, CV, and capital ships) could seriously derail US involvement. Imagine Line Islands and Hawaii in IJ control by early 43, and KB intact -- they perhaps could go marauding in CENTPAC and nibble away at NZ? A counterinvasion of Hawaii for the Allied player would be very risky with KB a force in being, plenty of air bases, and so much open water to CONUSA.
Regarding India, Ceylon looks a like a good choice. Another unsinkable carrier, but it is so close to India and so far from Burma that it can be isolated by Allied air later in the war and turn into a death trap. Prior, it can be used as a staging ground for raids and to effectively generate invasion threats against both Indian coasts.
Taking all of India seems again a huge gambit: a race for Karachi. Not sure it is really feasible since you get stripped of a lot of troops you have plan leaving behind as garrisons.
I usually try to grab the Calcutta area (against AI though) since there are several mutually supporting bases closeby that allow you to turn the area into a fortress. You can take and deny the enemy a lot of industry that way, and protect Burma by its flank. I guess that tactic isn't possible versus a human, though -- with concentration of US and british 2 and 4B your air cover around Calcutta could be defeated perhaps as early as autumn 42, and with a little invasion further East at Akyab or so the Allied player can turn Calcutta into a death trap.
Haven't thought about aiming for NZ a lot, but I recall that some people were discussing that also a few years back. Could be possible if you stage a successful coup against Nomuea and Fidji with KB intact, and might also be a severe pain in the btt for the allied efforts? But it is also very exposed and far from the home islands with the big shipyards.
< Message edited by janh -- 3/1/2012 4:14:49 PM >