I decided to use AM to fly from Toronto to New York's JFK airport since they are partners with AA who flies this route. (Air Canada only flies to La Guardia and Newark.)
I called about 1 month before my departure date (Oct 12/08), and got a recording that unless I needed to fly within 2 weeks, to leave a message and someone would call me back. They did call back 4 days later.

But I called the next day after my original call, and got through. I was able to get the exact flights I needed on AA from YYZ-JFK-YYZ.
Cost was 1050 Air Miles
AND $235 of taxes! Same itinerary on AA web site would have cost me $345. What an absolute rip off!
So yes, I will continue to accumulate Air Miles because it's a free program, but given a choice, I will use a different loyalty program. For example I have an MBNA Starwood MC and a CIBC Aerogold Visa. Also recently participated in a BMO promotion where I had the choice of 1000 Air Miles or $200 on a Mosaik MC gift card. After my JFK experience, I opted for the gift card!
I used to think the best value was to redeem Air Miles for travel rather than merchandise. I no longer think that way. Apparently, there are no taxes or anything else to be paid when redeeming for merchandise.
Also, thought I should mention that I did earn AA frequent flier miles on my YYZ-JFK flights. ^