Based on my experiences, I will not let Viking book my air again.
1) When Viking books your air, you pretty much give up control. They can change your flight as they see fit - EVEN IF YOU HAVE Air+. (see example below)
2) Viking air can appear to offer a good price, but that is often because they're going to give you a routing you do not want. To get the routing you DO want (e.g., non-stop), you'll have to pay the fare difference, thus eliminating what seemed a good price.
3) If you want to cancel the Viking air, Viking will not refund your money. They will only give you credit.
4) If it matters to you, you will not get credit towards an elite program (e.g., AA loyalty points) for your flight, because YOU did not buy the ticket.
A recent incident:
We had Air+ AND paid an extra $1900 to get the AA business class seat we wanted for a direct flight DFW-CDG. During the night and without asking us, Viking changed us to Air France. When I called, Viking first said the AA flight (AA48) was cancelled. It was not. Then, they said our AA reservation was probably cancelled because the flight was oversold. If the flight was indeed oversold, I rather doubt AA would start by kicking off an executive platinum elite. More importantly, I quickly established that the flight was not oversold and in fact there are seats available now. Finally, the agent said "I cannot get you on the AA flight. Would you like to book a different flight and pay the fare difference?"
Unfortunately, I have no way of knowing why I lost my AA reservation. Since the Air France business class seats are cheaper than AA, the cynic in me suspects Viking took the opportunity to make a few thousand $ profit by changing our flight.
One last note:
You are very unlikely to get any help from the Viking Air agent who answers your call. That person is essentially a human “bot” who types in your question or complaint and then reads you the pre-programmed scripted reply. They have NO authority to do anything beyond that scripted reply. Don’t waste your time, just request a supervisor.