Some examples I'm familiar with:
YYZ-MIA-YYZ
J class $2400 C class $1500
C class requires 7 day advance booking and 7 day minimum stay, 30 day max.
YYZ-HNL-YYZ
J class $3500 C class $2500
C class requires 7 day (I think) advance booking and 3 day minimum stay.
Remember, the Amex coupon draws seats from the C class inventory but does not necessarily have the C class restrictions. That's my understanding, anyway.