Yes, you can upgrade stays booked using Ovation certs by appliying room or suite upgrade certs. (see the master FAQ in the Fairmont forum for details)

However, upgrade certs are non-transferable except to immediate family (incl. parents) if you´re a Platinum member.

There are also Ovation certs which book into higher room categories or even suites, but I have no idea whether those would be part of the CC deal. (I´d guess not, but you never know)

Btw, rates at the Empress can be very affordable (at least for Fairmont standards), you just need to follow the various promos, sign up for the monthly Great Rates Great Dates newsletter etc. I´ve seen rates for standard room as low as $99/night during off-season and quite often you can find a rate in the $150-$200 range.