I'll give a nod to the Maxima, for the right price. I remember the previous gen touching $40K (sticker that is) when my buddy worked at a Nissan dealer - I remember thinking "man this doesn't feel worth it." Fast forward to last Christmas, we rented one on Maui for a week. I have to say, I was pretty impressed with the overall package, and our midlevel SV stickered for something around $35K-36K. So they're right on top of the Mazda6 signature.
Personally, I prefer N/A V6 to turbo 4 power, but strangely enough I don't think turbo 4's are out of place in an entry-level luxo car - both my folks' cars are entry-lux 2.0T's and they work quite well. I just prefer the smoothness and soundtrack of the 6, and the Maxima delivered on both accounts.
I also didn't hate the CVT. As a matter of fact it was a godsend on the road to Hana, as it enabled the VQ to stay at low revs and just putter along.
With regards to the back seat, I agree that it felt a little small given the exterior size, but there was still plenty of room in the back for 3 adults. Then again, in my family we're used to cramming in the back seat - the 'family car' for a few years was B7 A4 2.0T, with 3 adult children.
I've been talking with my dad on what he should buy for a car down in FL. The Maxima came to mind, and we might still go down and look at it. But he also brought up a late model Avalon (because Florida) and I have to admit it's a pretty enticing package for ~$20K for a late model 2017 with low miles. Not sure if that's too sedate for OP's wants, but to me it seems like a better deal than a late model Camry V6, IMO.
The Maxima was a good cruiser that didn't feel like a boat. I feel like it's a very thin line and they did a good job of walking it.
(the Charger was also our rental for a few days when we had more than 5 people)