Aeroplan collects fuel surcharge on flights operated by AC and LH, but not on flights operated by UA. Compare the cost of the UA option and I think it will be more attractive than the SWISS certificate.
It appears you are right about that(!). I am having a hard time finding UA flights for the time period I'm looking for, but maybe it's too far in advance? Do they release more rewards seats as time goes on?
Thanks,
-d