We've just moved to Taipei. I've had a Visa Advantage card for many years and have been collecting miles on American through purchases and flights. United seems to have better flight choices to Taipei from NY, so all of our recent flights have been with them.

We're about to fly to London - there are nonstop flights from Hong Kong - and it seems to me that perhaps I should start collecting miles on, say, Cathay. Or maybe Singapore? That way, I might be able to buy an upgrade once in a while.

Should I slow down on one of my US carriers (probably American) and concentrated on UA and an Asian airline?

What do you think? You guys are the experts!

First, consult http://www.webflyer.com/ where you can do easy comparisons of various programs.

Certainly Cathay Pacific's Asiamiles program is very highly rated, and has quite attractive redemption features compared with some others. OTOH some fare classes don't earn miles at all, so you need to look at the Webflyer analysis and your own flying patterns to decide if it's the best fit.

Regardless, if you are traveling more than a couple of times a year and/or in business class, you're best off by concentrating your miles in as few programs as possible, aiming to attain elite status with somebody. Since Japan Airlines is joining Oneworld (American, Cathay, BA, Qantas et al) sometime soon, you might want to think about getting status with a Oneworld airline, since you'll be able to earn and redeem across several airlines' programs, have lounge access, etc.

My face is bright red... I thought Webflyer had a full analysis of Asiamiles, and... oops. Try www.asiamiles.com, or the CX board at www.flyertalk.com for details.

Like Gardyloo says, most CX discount fares don't earn miles, except in Alaska Airlines' FF program. Basically only full fare CX economy will earn CX or AA miles.

Second, I think you should first decide which airline(s) to use, then decide on the FF program. Since you're concentrating on UA miles, then while not stick with them and use Star Alliance carriers like SQ, Asiana and ANA? It's a little less convenient for LHR than Cathay, but how often are you going to London?

Now, if you're flying full fare Y or business or first, then it's a little bit different.

I think the OP said s/he has been booking to AA but (as we know) AA is thin in Asia. So I was thinking about a compatible program with their current AA affinity.

If you are going to fly an Asian carrier almost all of the time it makes sense to get on that carrier's program in order take advantage of benefits offered only to those in their program. Like upgrades with miles, mileage bonuses for status flyers, and op-up pecking order. If you are going to be flying United mostly then just have the Singapore Airlines or ANA miles credited to your UA account. Good thing is that you will earn elite qualifying miles on any Star Alliance carrier.

"Soon" you will be able to upgrade on any *Alliance carrier using UA miles, but I bet it will require 30,000 miles on a Y/B international fare. It is only 15,000 miles to upgrade a Y/B fare don United.