I had to chuckle at MercedMike's comment about not going anywhere exciting. It depends on the river. The cruise we took on the Amazon was filled with more excitement than either of our big cruises on the Caribbean. Hearing monkeys howling in the trees, catching piranha, visiting with natives in the region, and exploring tributaries in smaller boats are just a few of the things we did during the 7-day cruise. Every day included outings that were adventurous.
We are preparing to go on a European river cruise, and do not expect the same level of daily adventure, but do expect some great wine tasting excursions.