Hi OP, based on your flying pattern, I wonder if you are better off paying for the benefits as you use them, rather than spending $xxx on a MR.

As you've concluded, getting AA PLAT is the easiest path to what you want (earning extra points and international lounge access). Unless you get very lucky, (a well timed status-challenge combined with necessary travel and good fare to your destination), you are going to shell out extra money on MR, or higher AA fare to gain this status. I estimate this extra money is in the order of hundreds of dollars.

Lets put a number out there: $500 is the cost of obtaining this gold status. For simplicity sake, lets say you get the status early in the year, so it applies for 2 years. How many seat upgrades do you expect to get, and how many times will you be using the international lounge, and do they add up to $500? This is not straight forward math. For example, someone may think a lounge visit as being worth the full price of a day pass ($50?) because they assume they will drink at least $50 worth of alcohol. To me, it is worth closer to $20 because the possibility of taking a shower. If I don't need a shower, it is worth closer to $0. (If I want a coffee/soda, I can buy it anywhere). similarly, what is a domestic upgrade worth? If you are flying the red-eye from SFO-JFK, an upgrade to a comfortable seat would be really nice. However, you said you only buy coach tickets, so you are willing to fly coach. How much are you WILLING to pay for the upgraded seat. That is the real value you need to put in your calculation. Not the retail value of the upgraded class ticket. EDIT: I forget to add in the calculation - How many more points will you gain with the PLAT status? How much is that worth? ($0.01 per mile is reasonable) Remember that you may not be doing all of your flying on AA, so be realistic in your calculation.

From your described flying pattern, I would suggest you don't worry too much about status, and just fly whichever airline based on price and schedule. Do continue to collect miles. :-)

As per your subject question: AA may introduce a spending requirement for status tomorrow. You would never know...

That may make more sense. Out of curiosity, when you have Gold status in any airline, what has been your success rate of an automatic upgrade to a higher class? I understand on some airlines you get complementary preferred economy, but for me I am more interested in an upgrade to business or first.

I have never gotten an upgrade before, so I'm not familiar with the process. In your experiences (anyone can answer this), what are the chances of getting a full class upgrade in Gold status and Platinum status (on any airline programs)? Does one program give more free upgrades than others? Does one stand out in the domestic or international upgrades, etc?

What do you mean by gold? Lowest, mid or highest tier? If lowest, you won't see that much recognition. There are so many people out there with the lowest tier.

Regarding upgrades, your chances are pretty slim and unforeseable.
On domestic flights you're probably always going to be overtaken by the highest tiers receiving complimentary upgrades. And if you're not, anyone who purchased a higher fare class is going to be upgraded if the flight is overbooked.
On international flights, it depends on which airline you fly and how they handle overbooking-situations.

I got status with BA and was upgraded on LHR-JFK once from Eco to Eco+ and from JFK-LHR twice. When did I get it? Once at BP check at T5(LHR) and twice at the gate in New York. Always was a nice surprise, but still, it's just Premium Economy.
I can't exactly speak for AA or other airline's policies, but on international travel you'll probably never see complimentary upgrades. As for IRROPs or overbooking situations, they'll most likely go down three lists: 1st depending on fare class purchased, 2nd their own tiers, 3rd alliance tiers where 2 and 3 could be intertwined. E.g. AA will certainly upgrade their highest tier before BA's highest tier, but might upgrade BA's highest before their second-highest. But that's certainly nothing you can count on.

They might also upgrade you to give you "a shot" of the higher cabin, maybe you'll spend more?
US based systems however give you at least some kind of domestic complimentary upgrades. Then it just depends on the status-load of the flights as well as the cabins (size/number of seats).

Per my understanding, and according to Delta's website with lounge access policies, this option has been changed, you don't get free access from its Reserve card anymore http://www.delta.com/content/www/en_...-of-terms.html it's $29 per person per visit now.

Your understanding is entirely incorrect.

Lol true, I might be thinking about the new "changes" with United Club membership. :P

If there is no way to avoid qualifying dollars (without a CC), then is there a way to gain QD on spending besides airfare? Such as a hotel, or other things? I am finding it is easier to meet the QM, but since I fly economy, it is very difficult to hit the $3k mark to get Silver. So I was wondering if there are any alternate ways to hit that 3K mark?

To what extent does UA audit? This isn't an issue for me now as I actually living outside the USA, but there may come a point in the next year or two where I will be living in the US, but as a temporary worker on a temporary worker visa, while maintaining my billing address and foreign credit card. But of course trips would be originating out of the USA...so would they audit that fiercely?

Now what about someone who is passionate about flying who has a friend or relative with a Canadian address...

Just read on this thread that one can avoid the PDA requirement for UA status by spending $25k on the card in a given year. (I assume that one still needs to hit the 100k mileage requirement.) Is that right? Is there a specific United credit card that one needs for this?

The PQD waiver via card spend is only available for Silver, Gold, and Plat status. There is no card spend PQD waiver available for 1K status.