We arrived in Istanbul several days early to explore the city with the three other couples in our group, using Tours by Locals online in advance of the trip to find a guide.
This was our fifth cruise, but our first on Viking. We had a wonderful experience, with great food at all venues and uniformly excellent service from all staff members. This ship is beautiful, and even our "deluxe veranda" cabin was great--not large, but very well designed and comfortable, with enough room for my husband to do his yoga poses there every day. (We didn't get a chance to try the fitness center and classes offered there, due to schedule conflicts, but I know group yoga and pilates classes were offered.)
We loved the fact that Viking includes so many things that other cruise lines have been charging extra for in recent years (e.g., one included tour at each port, a veranda for every stateroom, free meals at all venues including the specialty restaurants requiring reservations, wine and beer included at lunch and dinner.)