My first thought was wheelset. Some are just better than others for us bigger folk...and some are just completely out of the question.

This was actually one of the first questions I asked at various shops when I was looking for a road bike earlier this year. i.e. How will my weight factor into my choice of bikes?

The consensus amongst the people I talked to seemed to be that for the type of bike I was looking at (entry level road bikes), bodyweight probably wouldn't be a big factor. And if it was an issue then it would be mostly about the wheels, which is a pretty easy to solve "problem".

Good luck with your search!