The first question is, "take a 3, 4 or 7 day excursion"? If my count is correct, the 4 day trip has one more outing on the skiff than the 3 day excursion. The 3 day trip explores one of the two rivers that officially form the Amazon. The 4 day trip explores the other river. In both you will do virtually the same, see wildlife from the skiff, hike thru the jungle, visit a village, its school and living quarters for a family, fish for piranhas, swim and likely see pink dolphins. The seven day trip does everything virtually twice. My travel companion and I did the 7 day trip and enjoyed every day of the adventure.
While I never counted since many of the crew you hardly ever see, AE reports a total of 23 and to a person they could not do enough for you. It was quite amazing. Breakfast was my favorite meal followed by lunch. Evening meals reflected really local cuisine. A couple of nites the meal was outstanding...a couple of nites, just interesting, but I never went hungry.
The detail they go to was just outstanding. An example, sitting on my bed just before dinner one evening, a tiny bug crawled across the white sheet and I squashed it with my thumb. It left a tiny black smudge. When I returned from dinner the sheet had been replaced. Oscar, our cabin steward was the best and we enjoyed his skill at folding animal towels.
Very comfortable...quiet when the boat was underway at nite.
Boat sailed and returned to Iquitos