If your main goal with the extra money is to maximize your net worth, put it in a retirement account. That could be your 403b, or an IRA with another company like Vanguard if your 403b investment options are not great, or maybe a taxable investment account if you're planning on retiring before you can access the 403b. Your interest rates on the two debts are low enough (especially since both have tax deductible interest) that you can probably get a significantly higher return on your extra money by investing it in stocks and bonds.
For the 529, decide about how much you'd like to have available to give your kids for college and find some investment calculators online. You should be able to get a good idea of how much you need to put in each month to reach your goal. Once you're putting that much in, there's no need to put more in. Just check in on it every year or so and make sure it's on track to meet your goals.
However, if the idea of not having any debts is emotionally appealing to you and your husband, it's certainly not a bad idea. Financial decisions aren't all about the numbers.
My wife and I do sort of a hybrid of the two. We contribute enough to our 401k's to get the full match, then max out our Roth IRAs, and anything that's left over after that goes into the mortgage.