the Aeroplan website will usually force you to book Air Canada. You can sign up for the ANA mileage club. They have a tool there where you can see reward availability on any star carrier (Except Air China I think).
I use the ANA tool then Call Aeroplan and spoon feed the agent the flight numbers that have the availability. You have to suck up the $35 fee but it's worth it.
What dates are you planning on flying? how many tickets?
Oh and P.S, welcome to flyertalk!
