Depends on load, terrain, and distance. If your tours are 30 miles on rail-trails, you might get by with stock gears. For any significant load in any significant mountains, I'd want a (mountain) triple crank on the bike. Or if you're going more than 25-30 miles every day.

On a multi-day tour, Murphy's Law says you'll hit the perfect combination of a heavy load and steep climb at the end of a long day, and you'll need lower gears. Just a 4 mile, 6% climb towards the end of a 50 mile ride this weekend had me headed for my granny -- almost the only time I've hit it this year!