itn.com says it will cost you C$4466.00 including coach on the (U.S.) domestic segments and on DCA-YYZ. I tried specifying First for the domestics but it still came up coach.
What you have to do is figure out what cities are valid for your connections. Look up simple round trips on AA on expedia and use that as the basis.
For instance, MIA is a valid connecting city for YYZ-CUN, which should give you YYZ-MIA-CUN-MIA. But is DFW a valid connecting city for MIA-DCA or MIA-YYZ? Or (backing up) is MIA a valid connecting city for CUN-DFW?
And if DFW is valid for connecting MIA-DCA, is DCA valid for connecting MIA-YYZ?
That's how I work these things out anyway. And remember, sometimes throwing in one more segment turns it into a multi-fare itinerary (don't know the technical term) instead of one long routing.
Also it's possible the fact that some are in coach may be throwing things off, since that fare might not allow the stopovers.
andrew
andrew