I am 6'3" and about 250 Lbs. I have a Specialized saddle on the tandem. It is flat and hard as a board. It is comfortable for me.

I also have a couple of Fizik Arione R3 large saddles and they are my current saddle of choice.

Fizik used to market their saddles based on how flexible you are. The Arione is for very flexible people, and that definitely describes me and works for me.

​​​​​​Somewhere on the Fizik Web site they talk about which saddle fits which level of body flexibility. You might want to check it out.