I was just looking at the website of R+E Cycles. They've outfitted a "famous" tourer named Willie Weir with a Rodriguez touring bike. It features Campagnolo components. Here is an article by the builder on why he made that choice.

Triple cranks are REALLY that important for touring. A wide range is good, a high top gear is fine, but a really low low gear is CRUCIAL. There will be long hills, mountain passes, etc. where you'll need the lowest possible gear - low enough that when you're pedaling at a normal cadence your bike is going slow enough that it takes concentration to stay in upright in a straight line.

YES, you need a beefy wheelset for loaded touring. Breaking spokes is a common problem, and it's a drag. Get strong, well-built hubs, strong rims, use butted spokes. Use at least 36 spokes for the rear wheel, and consider 40 if you're a Clydesdale, or if you'll be carrying a huge load. Also, consider wide tires - at least 32, but some people go up to 40 or 45. The rolling resistance may be a tiny bit higher, but you'll get more cushioning, which will not only make you more comfortable, but, more importantly, help avoid breaking spokes. It also makes life easier if you have to make occasional forays off-road.