I thought 32mm was pretty much a standard road touring size. I tour on much narrower, but tour ultralight. When I packed heavier 32mm was what I used.
FWIW, I'd suggest that you allow plenty of clearance to allow for a little wobble in case at some point you have spoke/rim problems. It can make the difference between being able to continue and not, so I wouldn't max out on size that fit the frame.