I think you're in a tricky, yet enviable position. DB pensions are nice to have (and by that I mean golden), and I am going to make some assumptions as to which plan you belong to, but the HOOP pension fund I expect you belong to is well funded.
Short of regular income tax deductions, I don't think there is much you can do. If you don't do your own taxes, try it and use something like Quicktax. There are alternate areas that allow for further deductions, e.g. medical expenses, which may be something you can use. Rent and transit passes are deductable, and since it appears you are paying for your children's education, have them pass along the maximum amount of tuition credits to you, so that you can reduce your income taxes.
And don't feel bad about paying down the mortgage, even with rates being low. While you could have made more money investing elsewhere, your overall future risk decreased as a result (cost predictability).