I have a 2014 S 85 and my wife has a LR RWD 3. I'm picking up my own base SR 3 this Friday and trading my S in. The 3 feels so much better to drive and her 3 has become the family car because of the range that my S has become a commuter. Not worth having it for that use. I might miss autopilot, but again, her 3 is the one we take when we do long drives which is when autopilot is primarily used.
In our experience, the 3 fits our 2 kids and their carseats just as well as my S. The trunk and frunk space are definitely not as big as the S, but it hasn't been a problem with her car so far.