Save a ton of money and just buy some new seats if you really like your Forester.

Oops! 311 already mentioned this option... I can read... I swear... <img src="/images/graemlins/blush.gif" alt="" />

To me, Chevy/GMC truck and SUV seats seem pretty comfortable. Almost like driving a couch on wheels. Plenty of crumple room, too.

The more upright seating I find in truck/suv types. I have a Checy truck now as they are cheaper than an SUV but with an extended or 4 door cab can still carry people but still have the bed for carrying lots of camping gear.
A mid/large car like my wife's Impala is quite comfortable too.

Do you need real 4x4 as in transfer case with low gear for off road trails or just the AWD type you get on a lot of smaller cars?

Too much crumple room. I don't see a lot of sense in having the vehicle crumple to absorb shock if it is going to keep on crumpling until you are squashed. I took the course in vehicle extractions & I always thought that it would be better if the part with the passengers was rigid. Then the front part could crumple & stop at the dashboard so as to avoid crumpling the people. I have had to take crumpled people to the hospital.

Perhaps some people can modify the uphostry of the seats and add more cushioning. You should not ignore this option. It would be the least expensive.

I thought about changing seats long and hard and in the end rejected it. I just feel so cramped in the front. There is barely any room for my long knees, and I can't seat upright because then I hit my head on the roof.
<img src="/images/graemlins/grin.gif" alt="" />
So, new car it is.
The weird thing is that not a single person who drove my car liked the seats: both males and females, toll and short, skinny and not so skinny. <img src="/images/graemlins/laugh.gif" alt="" />

Which model GMC/Chevy SUV would you recommend? How is the reliability?

Either 4x4 or AWD is good to me. Right now I have AWD, and it works fine.

GMC Yukon, with leather seats. Large, roomy interior and a pleasure to drive. I often drove 14+ hour days, stopping only for gas/potty breaks, and was comfortable doing so in my Tahoe's/Yukon's.
I had smaller SUV's, and after a long drive, was usually cramped up, and miserable.