I certainly don't feel bad for wasting AA's time, but I don't love wasting my own. I was hoping someone might assure me that it was worth the pain of dealing with AA customer service for this kind of open-ended trip. I realize I'm wasting the same amount of time, but I don't mind spending a fair amount of time browsing websites to plan the perfect trip. Spending hours on the phone with someone who isn't really trying to help me infuriates me. To me, it feels like the difference between playing a fun game and, I don't know, talking to AA customer service.

Two things:

-Checking aaward availability over the phone won't take you more than 20 minutes if it is a simple itinerary.
-It is not really that the agents are not trying to help. They just tell you what is available and what shows up on their screen. I am 100% sure that the agents have no desire in lying to you or hiding things from you. If they tell you that there is no Business or First aaward seats on that LAX-LHR in August, well, it is because it is NOT available.

All I am saying is that there is an alternative to getting the "no longer available" dreaded message and it is not a big deal to call.
I do understand that scarce aaward availability is annoying and even more annoying that AA's website is so behind the times that it can't show real inventory.

Am having some issues with the AA booking site. If I enter origin and destination everything works fine. However, if I use the multi-city function for the same routing (e.g. in order to choose a particular connecting airport), the site seems to work fine and offers me various options (at the normal prices), but once passenger details are entered and confirmed, I get an alert saying that the fare is no longer available. I tried dozens of different routings/options, always get the same error message. Is this a known issue with AA multi-city bookings?

Multi city works well for what it is intended - trips consisting of visits to multiple cities

For trying to piece A-C via B via certain airports, it doesn't work so well

with multi city , it checks price and availbilty on a sector by sector basis(A-B and B-C , however this may not price up the correct fare for A-B and availability may also be different

Is the airport you want to connect at , valid for the journey which you are planning?

Thanks for that, makes a bit more sense now, ie why none of the options worked.

Yeah, the connecting airports that I am looking for also come up on the normal A-B booking, but not necessarily with the 'right' times.

Let's say I was looking for LAX-PHL and wanted it to be via ORD. The normal A-B booking might give me two options for that, say Flight 1 for LAX-ORD and Flight 2 for ORD-PHL, as well as the second choice, Flight 3 for LAX-ORD and Flight 4 for ORD-PHL. Both choices are priced the same. What the normal booking function does not give me is a third option, namely Flight 3 for LAX-ORD and Flight 2 for ORD-PHL. Connections times etc are not an issue. But the normal booking function just does not give you all the possible choices. Multi-city does give you those choices, e.g. flights 3 and 2, at a similar price too, but then, just before payment, it comes back and says that those fares are not available.

Have you tried pricing up A-C with a flight by flight selection using ITA and then making use of bookbymatrix to get it ticketed?

Ha, just trying it as I write this. And indeed, it does the trick, right flights, right price.

But you got to book via Flight Network or Kiwi. I always book through the airline directly so this would be a new experience for me. Do you have any experience with Flight Network or Kiwi? Will they give you a booking code so that you can then go back to AA and book seats etc?

I booked a WY flight with flightnetwork last week - completely painless; received email confirmation with both its reference and the airline reference

Trying to book MSY-NCE RT 5/24/2019-6/8/2019 (within the window of availabilty). The web site lets me select flights, and prices them. But when I get to the payment screen, it says "One of your flights is no longer available". I've tried several different flights and dates in both directions; the result is the same. These are code-share flights with BA. Is there some trick I'm missing?

The trick you're missing is probably the one being played by the carrier.

It's not uncommon in all types of travel to be able to get prices for products they're not actually selling. There are a few cases where I think it's a deliberate bait-and-switch but most of the time I think it's a system glitch.

In theory you can occasionally be viewing a product/fare that's available but while you're deliberating on it, someone else books it out from under you. And that's probably what customer service will tell you is happening, but of course it's nonsense when it happens over and over. You just have to accept that the fare doesn't really exist. Sorry.

It happens all the time, both with paid tickets and awards. Search for 'phantom.'

I had a similar issue with booking a codeshare where the operating carrier was BA. I believe the issue was to do with a 5 minute difference in the departing flight times between the BA operated flight and the AA code share. Now, that said, when I rang AA to see if they could book it for me they couldn't get the same price that their site and Matrix were showing so that does give credence to the phantom availability argument. In the end I ended up booking a different combination of flights that avoided using a codeshare but I had to switch the POS to UK instead of US.

Are you searching for MSY-NCE or seatching as 2 (or more) segments MSY-xxx/xxx-NCE ?

If the latter, it could just be a married sector availability issue - A-B may be available in a particular booking class and B-C may be available in the same booking class , but not as A-C via B

The individual searches wll be ok, but when it goes to price it, it will check for through availability and then say that the flights are no longer available

Searching for 2 biz class MSY-NCE seats, one PNR each.

The AA web site, the AA iOS app and the BA iOS app return fares of around $4000, but you can not book it, and no alternatives are presented.
The (new) BA web site, however, presents fares of $18,000 per seat. So it appears there is indeed a glitch.

I called the AA help desk, but the hold time was 45 minutes. I'll try booking again in a day or two.

Thanks all

Well, the American web site let me book on July 19, a week exactly after the stated availability period. Interestingly, the price was $500 more per person than on the BA site (not including seat selection fees).