It's always tough when you fall outside of the norm and if you're taller and heavier finding the right bike can be a pain just as it is when you are smaller than everyone else.
We have a few really big guys who have been coming to our co-op on a regular basis to see if anytihng has come in that would be suitable for guys who are 6'4 and 6'7 and not lightweights.
I was happy to hook the first guy up with a nearly mint mid 80's Kuwahara sport touring bike with a 25 inch frame and recently had an equally minty Norco road bike come in with a 26 inch frame so I'll be making a call on Monday to see if the fellow who has been looking is interested.