I don't own a minivan, but have rented plenty of times. Honestly, a minivan is tops in terms of convenience. The large sliding doors allow for easy access. If you are in a tight parking spot, the door slides away rather than opening out. Much better to lift a baby carrier in than a regular car door. I've had a situation where the asshole next to me parks so close that the baby carrier can't fit in the opening. I have to back out and fully open the door. This is an extreme though. Another plus is the large rear hatch. Great place for a baby changing station even in rainy situations.
With our first child, we had a RAV4 and it fit everything we needed it to. If I could do it all over I would've gotten a minivan. I know minivans have a stigma and my wife refused to drive one. We met in the middle and got a Durango after our second child. It's a little smaller than the Tahoe, but effectively the same thing. If I were in your place, I would at least get a sensibly priced small suv and keep the FR-S as the weekend vehicle.
BTW, congratulations. Babies are awesome. If you thought the twins made you smile, just wait till your baby gets here.
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