I have a Jamis Explorer 2.0 comfort bike. I know they can be found as a year or two old and they can be found in a big frame. My only concern would be the front fork. As long as you aren't jumping curbs and things like that, it will be fine with your weight.
Good luck with your search.
__________________
2007 Jamis Ventura Comp
2006 Jamis Explorer 2.0
2000 Specialized Hardrock (bought used)
Swim, Bike, Run and sounds like fun