have frequent flyer miles dictated who you fly with?

i wrote about how i chase status on the star alliance a few days ago. i took a look at my booking patterns and realized that yes, frequent flier (FF) miles do actually dictate who i book with.

of my last 32 paid transborder/international segments in the last 24 months, i have:

• 3 segments with air canada (2 of which were re-bookings post cancellation)
• 2 segments with us airways (both of which were re-bookings post cancellation)
• 27 segments with united airlines

not surprisingly, i do have a booking algorithm that i have when booking. this assumes that both airlines:

• have flight times that fit within my desired schedule
• do not exceed a pre-determined maximum number of connections

1) domestic travel
if westjet (WS) and air canada (AC) are the same price (comparing WS fares with AC's tango fares), i'm pretty neutral. i'm willing to book on AC simply because of the bonuses of status and the in flight entertainment which i think is a lot more flexible than WS'. if westjet is a few dollars cheaper (my threshold is 5-10$ -- a very small threshold), i'll book with WS. at least with WS, i will get 100% non-qualifying miles via their partner, american airlines. (note: only valid on fare codes Y/V/B/Q/L/M/P/G/X/D -- they don't make it easy to find on their own website,  but fare codes can be easily found via expedia or the on the fly app on iphone). this is in comparison to the 25% non-qualifying miles that i can get with AC.

being based out of YVR, it's quite easy to drive to SEA and fly from there back home to canada, although it's certainly more inconvenient. recently, i flew to ottawa from seattle instead of vancouver so that i could earn 100% status miles on united (UA). on a semi-mileage run, i booked SEA-SFO-IAD-YOW to maximize the points while paying a cheaper fare than what YVR-YOW direct would have cost.

2) transborder travel
recently with AC, they re-arranged some of their booking codes to include fare codes T/L/K in their tango category for international flights. unfortunately, this means that for many other frequent flyer programs (like asiana airlines), all T/L/K booking codes, regardless of whether they are flex (previously tango plus) or not, now only earn 50% miles. flights within canada or between canada and america can be labeled as flex but are booked under fare code T/L/K. frustrating, really.

if i leave from vancouver, i will choose a star alliance carrier over a non-star alliance carrier. if the price is the same and i can get 100% status miles on asiana airlines, i will book AC. otherwise, i book with UA. non-star alliance carriers need to be 100$-200$ cheaper for me to book with them as that is the cost of a) baggage fees, b) extra time needed to travel without the benefits of status, c) cost of lost status miles.

3) international travel
AC has quickly made many fares for international destinations into tango fares. not that they made these fares any cheaper, rather, they simply reduced the mileage earned to 50%. UA, in contrast, still provides 100% on all economy fares. their prices, at least out of YVR, are close enough to AC's to justify the extra cost for double the status miles. therefore, in order to maximize mileage, i have started to hunt around on competing non-AC star alliance carriers. for instance, there is a trip to hong kong and another trip to mumbai being planned at the moment, and i'm finding myself looking more and more at UA rather than AC. for the same price, why not get twice the miles?

short conclusion:
yes -- the availability of frequent flyer miles really does affect which carrier gets my traveling dollar. what are other variables that you use to determine who you fly with?