Use miles for air tickets, there is an important question is: how much fuel surcharge to pay?
Because many of the airline's fuel surcharge are surprisingly high, even more expensive than tickets themselves!
And alliances among different airlines for the tickets, and some will be exempt from the fuel surcharge,
So before with miles for tickets, fuel surcharges are studied.
ITA Matrix (http://matrix.itasoftware.com/) is an airfare search site,
After you enter your departure and destination, ticket prices will be displayed, and then click set out tax and surcharge.
For example want to use Phoenix companion for Air China to United States air ticket (from Beijing for the time being):
1. a return ticket from Beijing to NEW YORK, air found at about CNY8300, click on enter
2. will display detailed prices, YR, YQ, airline surcharges, visible air approximately CNY2100 additional charges,
25% of the full ticket price.
3. But on the other hand, Phoenix Salon also available for Cathay's ticket (see article), or for Star Alliance flights, might as well check fuel surcharge starting from Hong Kong to NEW YORK,
Pretty astonishing … Surcharge for only HKD384 (Cathay Pacific and Asiana Airlines in the Star Alliance)!
In terms of these trips,
As Macao residents journey departing from Hong Kong more in line with demand
Considered that Hong Kong needs more miles, but cheaper than the tax of about HKD2200! View more convenient,
Changing the Covenant or Cathay Pacific better (unless you want to travel and play in Beijing, of course, also included Macao-Beijing costs).
Finally, remind, with companion for Star Alliance/Cathay Pacific tickets, because it is across different airlines, procedures more complicated considerations, please see this.