It sounds like you're in need of going up a size class from the MKC. You might find the Jeep Grand Cherokee interesting, if you can get past Fiat/Chrysler products being remarkably unreliable. If you can wait, the 2016 models should be very interesting, with a new MKX, new RX, new SRX. If we'd wanted something larger, the new Volvo XC90 plug in hybrid would have had our attention.
We recently made a couple hour trip to the Stetson Mansion (btw: incredible!) with a couple friends, one of whom is over 6'. My wife did move her seat up a bit more than usual to make more rear seat room, and we leaned the rear seat back a little from the default upright position. Both friends said the rear seats were really comfortable. They also enjoyed the openness of the big sunroof.
We recently made a couple hour trip to the Stetson Mansion (btw: incredible!) with a couple friends, one of whom is over 6'. My wife did move her seat up a bit more than usual to make more rear seat room, and we leaned the rear seat back a little from the default upright position. Both friends said the rear seats were really comfortable. They also enjoyed the openness of the big sunroof.