We are looking forward to trying Primetime on our trip in Nov, especially interested in trying the PB&J milkshakes!
As for Sci-Fi, I did not care for it. I ordered the "safe" burger, and it was burnt to a crisp. I didn't send it back because my mom was already annoyed that she was sitting in front of us and unable to join in any conversation without turning around. It was SOOO dark, and the little table space you get when eating in the car was so claustrophobic to me. It is really, really dark (ie, I had to literally take a pic of my food with the flash to see what I was eating!). Most people enjoy the atmosphere more than the food, but both were a turn-off for me.
With your odd-sized party, someone will likely be in one bench seat by themselves, with no one to talk to unless they turn their back. Even if you configure it so that everyone is sitting with someone, you certainly won't be eating as a "group".
We will only return here if it's just DD and I, and she begs me. But I don't think she cared one way or the other, and her pizza was straight from the microwave. Blech!