Four neighbor couples recommended a Viking cruise when I was considering a summer adventure. When I received a catalog for free airfare, I decided to book! I still had to pay extra being a solo traveler; so I reserved a lower cabin. I didn't book extra night(s) before or after the cruise. I used Viking Air Plus for $50 extra to reserve flights, convenient for me.
I missed seeing Amsterdam because the ship docked at 2:30 am; and I had to leave for the airport at 5:30 am for an 8:00 am flight. I consider it a mistake that I didn't experience a beautiful city and museums.
Onboard I felt amazingly pampered by the staff, in my cabin, in the restaurant where the waiters knew my name! I enjoyed delicious food every meal. I'm an early riser so dined alone in the Aquavit Terrace at 6:00 am. Lunch and dinner in the beautiful dining room, sharing a table with lovely people from different places. I liked the evening meeting to prepare us for the next day's tour. I didn't attend the late night games or music events.
The cabin was clean and refreshed twice a day with products, water, and linens.
The steward was polite, neat, friendly. My window to the river was just above water level.