Shamrock, I can't think of a traditional spoke size that hasn't been used successfully on a touring bicycle. The strength of the wheel is in the build, IME.

While I do favor butted spokes, both of my touring bikes currently have straight gauge spokes. One is the common 14 gauge and the other is 15 gauge. The one with 15 gauge spokes is a very high mileage bike that carried four panniers. This is it's OEM wheel set from '96, but there are a couple of 14 gauge replacement spokes on the rear wheel.

Because the one with 15 gauge spokes is mainly my beater bike, it will receive my 14 gauge wheel set once the '96's rims die. The wheels for my main touring bike will then be built with the DT AlpineIII triple butted spoke because I like the thicker hub end.

Brad