NRG today report a Pesak Halakha by Rav Ovadia Yoseph that is full of common sense.
Rav Ovadia said that if having seperate seating at a wedding will cause family friction, then there is no problem with having mixed seating! He appreciates the fact that frequently families prefer to sit together at a simcha. And of course Rav Ovadia understands that Shalom Bayit is more important than a mechitza in these circumstances. It is just sad that piskei halakha on public policy issues that reflect common sense, sensitivity and halakhic expertise, seem so rare!
For more on the topic see here. To the best of my knowledge, Eli Clark wrote a scholarly article about this in the Journal of Halakha and Contemporary Society some years back.