Assuming that the merger between American and US Airways is actually consummated, we know that the combined entity will be called American Airlines and will be based the Dallas Fort Worth area. The frequent flyer program will be AAdvantage and the airline will be a part of the oneworld alliance (US Airways is currently a member of Star).

On the merger announcement day, Doug Parker explained that he learned a lesson when integrating US Airways with America West — it’s better to take the IT architecture of the bigger airline, rather than migrating the larger data set into the software platform of the smaller carrier. He thought that lesson was applied well when Delta and Northwest merged. And he was presumably too kind to say it, but the disastrous effects of ignoring that lesson played out in 2012 when United migrated to the old Continental SHARES system.

With US Airways miles becoming AAdvantage miles, and presumably retaining the AAdvantage computer program, we also likely get the AAdvantage award charts. There may be some modifications along the way, but we can expect to lose the character of the US Airways charts. And even if that weren’t true, we would be able to expect to see many of the unique values in the US Airways chart harmonized away (there are also some real disadvantages to their award rules and chart, but here I’m talking about the gems).

So I started to ponder what I’ll miss the most about the old US Airways Dividend Miles once it’s gone.

1. US to North Asia for 90,000 miles in business class and 120,000 miles in first class.

2. Enroute stopovers often won’t change the price of an award. Flying to North Asia (like Hong Kong or Beijing) is less expensive than flying to Europe even if you transit the Atlantic and make a Europe stopover on the way. It’s cheaper to fly US – Frankfurt (stop) – Hong Kong and visit both places than just to fly to Frankfurt.

3. Seemingly contradictorily (although it’s not once you understand that awards don’t autoprice) often the first stopover city will determine an award price. If you stopover in Tokyo enroute to Singapore US Airways will often price an award as North Asia (Tokyo) rather than the more South Asia (Singapore).

4. Domestic 3 cabin first class is the same price as 2-cabin first or business (50,000 miles). That’s great for flying United from New York to Los Angeles or San Francisco for instance, why fly business class on those routes when for no additional miles you can fly first? Of course United is removing three-cabin service there anyway, so maybe the merger is coming at the right time.

5. Cheap Mileage Upgrades. US Airways mileage upgrades are based on flight distance starting at 5000 miles and $25, with the cash co-pay waived for elites on domestic routes. American charges more miles for most flights and hits up elites for co-pays on domestic flights (but does offer more confirmed upgrade instruments).

6. Phone Agents Who Don’t Know Geography. No, these sweet agents aren’t necessarily losing their jobs due to redundancy. But assuming that Doug Parker does what he says — keeps the IT platform of the larger airline, a lesson whose importance he learned from combining US Airways and America West (and presumably from watching United’s debacle last year), we lose the combined wonderfulness of US Airways IT platform which (1) doesn’t auto-price, the agent locks in pricing manually, and (2) instant ticketing. American’s computers price awards, usually correctly (although not always), and even if there’s a mistake in your favor that doesn’t mean it’s a done deal because reservations get queued for ticketing where they’ll be reviewed for accuracy — including that you’re not being undercharged. That may be the end of the creative routings between Australia and the U.S. via South America and Europe for no extra miles, may she rest in peace.

7. Cheap Australia awards. US Airways charges 110,000 miles for business class to Australia or 140,000 miles for first class. They allow you to route direct from the US, or to travel via Asia (and if an agent declines the routing, hang up and call back). It’s cheaper to fly to Asia and from Asia to Australia than just to fly to Asia, since South Asia roundtrips are 120,000 miles in business and 160,000 in first. Bangkok and Sydney is cheaper than just Bangkok, and Thai Airways has amazing availability to Sydney. American on the other hand wants 125,000 miles for a business class award — and does not permit Asia routings at all, except as part of distance-based oneworld awards which are pricier still.

8. Free stopovers on roundtrip awards, and not just at the North American gateway city

9. Routing through Asia to Australia for no additional miles and more generally none of the strange American AAdvantage rules that you cannot fly between region A and region B with a connection in a third region unless there are specific allowed exceptions (like flying between North America and Africa via Europe, or North America to South Asia via North Asia) and that you cannot fly between two cities on a single award if the most significant airline on the itinerary doesn’t publish a fare between those cities.

10. 30,000 mile business class awards within ‘South and Central Asia’ (roundtrip). Awards between India and Indonesia or Maldives and Malaysia for 30,000 roundtrip in business class. American charges 45,000 miles roundtrip within ‘Asia 2’ — and 60,000 for roundtrips between ‘Asia 2’ and the ‘Indian Subcontinent’

And here’s my bonus #11:

• Grand slam. That was probably my favorite promotion, it was downright fun, collect activities with thirty-someodd partners to net 100,000 miles, and it was a puzzle to see just how cheaply you could do it. (Plus it introduced me to Biscoff spread.) Sure Grand Slam didn’t run in 2012, but there’s been rumors about its return in 2013. The merger may put that on ice. But the specific promotion isn’t the point — US Airways Dividend Miles has probably been the most aggressive on the promotions front generally over the past 3 to 4 years, including outright mileage sales on the cheap. It’s that aggressiveness that may at least be tempered by the combination with American, a larger and more conservative program.

There’s plenty to love about the merger for the value of US Airways miles, but I started by pondering the things I’ll miss. Do you see your US Airways miles getting more or less valuable with the merger?