I started a thread about a week ago on the topic of front crank gears you may find useful.
http://www.bikeforums.net/showthread.php/760385-Granny-isn-t-everything!
We didn’t talk too much about derailleur ranges but the gearing was kicked around a lot. My theory may help you also as you mentioned in your opening post you are looking for "commuting and touring" setup. That also being what I wanted lead me to want my front center gear to be taller than what the mtn bike triple crank set I installed gave me. I had a 44-32-22 triple on it and hated it because half the time when commuting I wanted to be on the big ring half on the middle. If I only were to use the bike as a loaded tour bike I may have liked the setup better.