Everyone has really covered all this already, I was just going to add:

I did some touring this Spring without a triple crankset - I orginially had a 42-52 double crankset and a 11-27t cassette. I swapped the crankset chainrings to 38-52 (lowest BCD chainring I could use with that crankset) and the cassette for a 11-34t. This required a long cage RD, so I got the super cheap Shimano Tourney, which is ugly as hell but works just as well as my old 105 stuff. The 38 X 34t gear is probably somewhere in the low 30's in terms of gear inches, but it did fine for me for short touring, without any major days of complete exhaustion.

Most people shoot for a low gear between 17-24 inches for touring, but my 30-ish gear was fine for me.