We are a family of 14 people (4 generations!) who just completed a cruise of Portugal's Douro River on the ms Douro Spirit with Vantage Deluxe World Travel. It was the first river cruise for all but one of us and was a magnificent experience.
Douro River ships are small-ish, because the lock system on the Douro can't accommodate larger ships, but the ship was outfitted very nicely and our rooms were terrific. Vantage distinguishes itself with exceptional service -- everyone was extremely friendly, charmingly helpful, and genuinely kind. Vantage's travelers are a mature group of people, so our family stood out from the rest (ages 10 - 80). Everyone was very friendly and glad to share their cruise with such a relatively young and boisterous group. Vantage managed every detail like clockwork. The 7 day cruise was the centerpiece of a 13 day tour, and our accommodations off the ship were incredible -- Vantage put us up in two of the finest hotels I've ever experienced, including a hotel in Porto, Portugal that is actually a baroque palace built in 1742. This was an incredible experience, and we are now a very happy family!