I'll second all of the good advice here about your having a good chance of landing 2 CX F tickets. I've done that twice on two trans-Pacific trips with my wife, once 330 days in advance and another several months in advance. And sometimes seats are available even closer to departure dates than that. If the seats are available, there should be no problem with booking one with your AA miles and another with your wife's.

I'd also second chanp's advice about using awardnexus.com. It's free to FT members for moderate levels of use, as would be the case for you. It's a pretty simple system, but if you're new to the mileage game and have trouble figuring it out you can contact the fellow who runs it (ckpeter is his FT handle, I believe), either through that site or through FT.

A few other thoughts:

1. Are you sure that it's too late to get 75K AA miles through the credit card deal? I thought I'd seen posts in the MilesBuzz forum about the link still working, even though officially the deal has ended.
2. As you may know, you can and probably should get the outbound and return tickets separately via AA. It makes things easier in a few ways.
3. I'd enthusiastically endorse flying CX F both ways if at all possible--it's possibly the best award F deal that's readily available using miles, on one of the world's best airlines. Check out the CX forum or Trip Reports forum for more reasons why. More specifically, I believe that CX F is more commonly available than JL F (which I have to confess I've never tried) for an award, and transiting through HKG is easier than through NRT, and on CX you'd be in F for one long trip rather than breaking it up along the way in NRT.
4. Is Bangkok your main or final destination in Thailand? If not, I believe you can at least get to Phuket on CX or its affiliate Dragon Air on the same award ticket, directly from Hong Kong. If you do need to fly domestically within Thailand or even to Siem Reap in Cambodia (which I agree would be a good side-trip, though be prepared for the place to be swarming with busloads of tourists), both Thai and Bangkok Air are good and offer fairly inexpensive economy tickets.
5. [I originally posted incorrect info here. See my next post for the correction.]
6. The easiest way to find availability and book the seats is to simply call AA. But if you don't find exactly what you want, it might be worthwhile to check awardnexus to learn about options to suggest to the AA phone CSRs, since some of them might not find those options without a bit of prompting. And in either event, if you reach a CSR who seems ignorant, unfriendly or unhelpful, simply politely end the call and try again with another CSR.

Happy trails!

I'm under the vague impression that non-elites can make free changes as long as they don't change the routing (i.e., leaving on a different day or time or class but on the same route is allowed). But I'm not certain.