You might look at the Trek Navigator.
http://www.trekbikes.com/us/en/bikes/2008/bike_path/navigator/navigator30/
I have used one, a 21" 3.0 version, with some with great results and I'm sized similarly.
The seat post suspension, front suspension [which can be switched off if wanting a better speed on pavement] and wider 26" semi-road/semi trail tires also provide some cush, plus the relaxeed frame geometry allows a natural and more upright riding position.
I've now lost some of the weight and am moving into two other bikes. So, I happen to have mine up for sale in Phoenix Craigslist. I'm not trying to "plug" my bike for sale. I do say that my experience with the Trek Navigator 3.0 has been great.