Ok, here's the best I've found:
*CP discounts applied
United Airlines
$1684.00 incl tax and fuel
Calgary to Bangkok via San Francisco and Tokyo
Bit more availability on this fare and good connections both ways.
Singapore Airlines
$1695.00 incl tax and fuel
Calgary to Bangkok via Los Angeles or San Francisco and Singapore
Opportunities to stop in Singapore and Tokyo if you want.
Cathay Pacific
$1728.00 incl tax and fuel
Calgary to Bangkok via Vancouver and Hong Kong.
Most expensive option but in my opinion the best airline. Good connections and you get a free stopover in Hong Kong if you want. Return dates flexible too.
PM me if you are interested in one of these and would like an itinerary done up. Let me know your preferred dates and how flexible you are on them.
Cheers.
P.S. Note on EVA Air, they are a Taiwan based airline with a very good reputation (for the most part all of the Asian carriers have excellent quality - Cathay Pacific and Singapore Airlines have consistantly won 'best airline of the year' awards for the last decade)