We chose Oceania because we'd sailed with them two years ago in the Western Mediterranean on Marina. The Regatta is about half the size, and we liked the style and intimacy of the ship. The cabins are smaller than those on Marina, but we chose a Penthouse 3 because we spend a lot of time in our cabin and on the verandah; the size was fine.
The food was excellent; the restaurant service earnest but not always flawless. Most of the staff is young and comes from around the world. We ate in the Grand Dining Room for every meal, unless we had room service, because the Terrace Cafe was very crowded, especially with children running around. Apparently, despite their not-particularly-child-friendly position, Oceania does have a children's program of sorts (Explorer Club) on the Alaskan cruises in summer when family groups travel. We didn't like this because there is no real program for kids with separate facilities other than a room with chairs pushed against the walls and a carpet where kids play board games, etc. Sometimes we saw restless children running around in the halls and elevators.
Embarkation from Seattle was smooth and for us effortless because we stayed at the Marriott Waterfront Hotel across the street and just rolled our luggage over to Pier 66. Disembarkation was a different story at Canada Place, Vancouver. Two other ships, much larger, were also disembarking, and finding our luggage was challenging, even though Oceania had everything organized with colored tags; there was less space to group things.
The three ports we visited were interesting: Sitka (good hike in rain forest not far from dock, part of Oceania shore excursion); Wrangell (independent hike on John Muir/Mt. Dewey trail); and Ketchikan (the least interesting, crowded with other cruise ship passengers and full of tourist shops; the Misty Fjords shore excursion was long and not as interesting as we had hoped). Our time in the Tracy Arm Fjord was magical, seeing the azure sea and the floating ice, a glacier in the distance.
We went to one night of entertainment in the Regatta Lounge and found it to be mediocre; Broadway hits, many from Lion King and Fiddler on the Roof. Being introverts, we more enjoyed watching DVDs in our cabin from the ship's extensive and free DVD collection.
We attended one lecture, on climate change, by a Western Washington State professor. He obviously knew his stuff, but perhaps was a bit over the head of some of the audience when it got down to data and graphs. It was well-attended.
We were very happy with our Alaska cruise, and we're thinking of booking another Oceania cruise. They live up to their promise with service, helpfulness, facilities, and excellent food.