IMO--I don't think there is any advantage to 26" wheels. I have a high quality set of 700c wheels that are probably stronger than most stock 26" wheels. I also don't plan on using a tire wider than 32mm for touring. They are a good compromise between weight and comfort.

Part of our route last summer took us over 400+ miles of this type of road and trails. Also about 500 miles of cobblestones and paver block roads and trails.