I have been on tours with 2 different companies. I found that each had their own definition of easy/moderate/challenging. Trek Travel had climbs with 10-15% grades on tours labeled moderate. The people on the tour ranged from racer types who were 20 years younger than me, to people in their 60s riding hybrids. I was sort of in the middle. We didn't go for speed and sometimes didn't do all of the daily mileage (we had short, medium, long options). Mostly I did the medium options, because with all of the climbing, I didn't want to feel dead. Plus, it was rainy and 45 degrees at the beginning and 95 and boiling at the end.
We went to Canada with Classic Adventures and purposely chose a moderate trip that veered on the easy side, because we wanted a vacation, not just 250 miles of riding! I enjoyed myself much more, but the riding was very easy, because of the lack of climbing (there was vicious headwind on 2 of the days). So, you can sort of look and see what type of participants sign up for the company's tours and it might give you an idea.