Hi Cattboy, lots of info there. Let me see what I can do with it.

First, about what I meant about 25k miles and your question about what can you do with 4000 miles. The most basic part of mileage collecting is using those miles for award flights. You accumulate mileage, keeping a balance in the program. Then you trade those for a ticket. My statement was basically saying the major carriers in the US all charge the same miles for a domestic roundtrip award ticket, with that costing 25,000 miles. AA and UA also allow one way awards, for 12,500 miles. Some places and areas you can make use of lower miles. UA charges 5000 in the past for inter-island flights in Hawaii (but I think this is now 7,500). International travel requires more miles. (Also you have to find available seats, or you can pay more miles for a seat if there is no available at the lower level. So you really can't do much with 4,000 miles in your account. I don't use my miles for upgrades, but if you browse the forums for the specific airlines you'll probably find more details on how else you can use your miles, including upgrades.)

So lets apply that to your question about who to fly with. In your examples of the transpacific (TPAC) flights, you are considering paying an extra $200-300 to fly on AA & partners over NZ. This would net you an extra 7000 miles or so. Although I'm not one who gets exact about my math and value of miles, by my basic thinking that is about 2/3 of a domestic one-way on AA as an award for the extra $200-300 out-of-pocket. I don't see that as a great value.

The math changes again when you consider that this is one of the reasons you sign up for several programs. You can still get those 7000 miles, but put them into a United account instead of an AA account, then you're still getting 2/3 of a ticket, but for a few hundred dollars less. (Note: I think NZ sometimes has fares that don't earn on United. So this last part might or might not affect your exact example.)

So for me, this is rarely worth the difference in cost. I would maybe take Star Alliance for up to $50 more since I could probably book on United and get free checked bags worth about the same and get miles in the program I want. But I would never choose miles over 100 or more in price difference. I would just put those miles into my account on whatever airline had that fare or the alliance they are in. Sometimes I earn no miles, like if I fly a Low Cost Carrier in SE Asia. But the cash savings is worth it to me personally.

As you've seen though, others might value it differently and consider it "worth" it. Everyone has their priorities in this game. If you're close to earning high level status, where you will get free upgrades or some other benefit, then maybe the 200 is worth it to you. But if you're only flying 50,000 miles or less a year, and you usually just buy the cheapest tickets out there, I would not pay that much of a difference for a flight. Just open accounts in several programs and accumulate as best you can.

Other factors of course are route, aircraft type, entertainment, etc. which might factor into your personal value in choosing a route. One comment above values non-stops versus connections. The trip reports here on Flyertalk and on the blogs can be a good resource to judge some of these types of things.

As for miles expiring, it is important to note but super easy to get a few miles here or there to keep them active. You might sign up for awardwallet or a similar site to help keep track of your balances, expiry dates, account numbers etc. if you do join several programs.

About fares, usually you don't have to worry about a fare not earning miles on the airline you purchase and fly. Meaning if you fly AA and credit to AA, I don't think there are any fares that wouldn't earn miles. The only main difference in earning is the coach/business/first fares. The different fares make a difference sometimes in upgrades though. Foreign airlines are trickier in this case though, and sometimes some routes earn miles and others don't, even for the same fare code.

There is an Australian frequent flier website similar to this one that might be a good resource for you to find info on choosing airlines to use while in Oz and SE Asia.