I found your post to be a little bit vague. A determination as to how may bags and their location really depends on A) what type of touring you intend upon embarking on and B) how much gear you intend on taking. I mean in square inches not necessarily weight. For instance, I do full loaded touring. I would simply run out of space with the amount of gear I take on tours with less than four panniers. I have read that steering becomes greatly affected when you put more than 20 lbs on the front racks. On a side note: Personally I am against the frame bags, because of the importance to have easy access to several water bottles. Do tourists know that they need to drink close to a bottle an hour while riding?