I always calculate my points base one what is the quickest/easiest way to use them. for AMEX MR, it will be $0.01 as you can apply AMEX MR toward your travel transaction at $0.01 per MR. For AEROPLAN, I use a trip from YYZ-HKG in Y as my point of destination as I know I will always need to go to HK. And I use $750 to $850 (base fare only) as the ticket price ... so that make a 75000 = $750 to $850 or $0.01 to 0.01133 per AEROPLAN miles. Therefore, in conclusion I use $0.01 for both AMEX MR and AEROPLAN. Everything else that can I normally convert to AEROPLAN will then be based on AEROPLAN value. Hence Club Sobeys will be $0.005 per points as I need 2 Club Sobeys for 1 AEROPLAN.

But everyone calculation is different and everyone value it differently. I do not use a J reward ticket as I know I will never purchase one, so to me, it is not a fare comparision. I view it by how much money I will save / keep in my pocket by using my points. Some will view it by how much will it be if I need to purchase the exact same product. Both ways are correct, again it is all depending what works for you. If all your reward flights are within NA, your value could be much higher than my YYZ-HKG. For example, a trip from YYZ to YVR can easily be $450 based fare, so that 25K for $450, a lot higher than my 75K for $850.

Hope this help you in some way.