Yeah, my wife's back in school, so we go to lunch but beyond that we don't get to spend our whole Fridays together. When we were getting started Ryan would go on adventures with his family on Fridays, but my kids were already in school. YMMV on the family aspects of having Fridays off.
But I'm no martyr. If you think Friday with your family is awesome, you should try having Fridays with almost no responsibility sometime. It's pretty great.
For me, the biggest thing about having Fridays off is you actually get a day for yourself. My weekend is 100% spent with my wife and kids, so having a Friday where I actually get to unwind and do my own thing (hacking on Arduino, playing games, programming for fun, whatever) is crucial to my well being.
Before I had kids, this wouldn't have mattered since you already have 2 days a week you can do whatever you want. Having 3 free days a week vs 2 is not really that different. But after kids, and working 5 days a week, I had 0 free days a week for myself. Going from 0 to 1 free days a week is a HUGE difference.
But I'm no martyr. If you think Friday with your family is awesome, you should try having Fridays with almost no responsibility sometime. It's pretty great.