I will likely optimize Audyssey for the front row and not even involve the back row in measurements. This will likely be the kid's seats and they will not notice the difference.
I have my theater optimized for the front row, and more specifically MY seat only really. Even with enthusiasts who have come to demo the system, they have said it "all" sounds good from front or back row, and my room is a little more tricky than say RMK's as I have VERY little width to work with so side placements I had to sacrifice somewhere, and with the time and effort me myself and I have put into the theater, I wasn't going to sacrifice the MLP one single iota. For the casual listener they have never even noticed a difference even when I have adjusted the sound to work a little better for a "Big" viewing party. I say your thinking is right on with making it work best for where you plan on being while watching.
Another note on side placements is they should be relatively wide dispersion (if you are using s8/t8 etc then you're in fine shape) to distribute the sound and the closer you can get to on-axis with them, the better, but it still pretty easy to accomplish an acceptable sound from front to back row with them optimally placed (technically) for the front row...Unless your rows are like 10 feet apart