Opinions differ (naturally).
At least you have a logical starting point (the dimensions of your bikes). Many people set up their touring bikes the same as their other bikes, and it's not a problem.
Then there are those who want to move their handlebars up (in relation to the saddle) to gain a more upright riding position. One way to get that is to get a bigger frame. A bigger frame also gets you a longer wheelbase, which is desirable when you're carrying a load. But when you get a big frame, the frame gets bigger horizontally as well as vertically, which means that you will probably want a shorter stem, move the seat forward, get a seatpost with less offset, etc. Alternately, if the bike has a steel fork, you can use an arbitrarily large number of spacers to get the handlebars up where you want them, and just leave everything else the same.
Last edited by ploeg; 11-04-10 at 04:23 PM.