This is our 2nd Viking river cruise. We got a voucher from our first Viking cruise in Southern France as the A/C on that boat broke down in 100 degree heat for 3 days.
Anyway, I recommend the Basel to Amsterdam route as you are going with the river current and have more time docked. We had a room on the right side (starboard and odd numbered) and I would recommend having one on the left (port and even numbered) side as it will face out into the river more than into the river bank or dock.
The boat was still spotless and the crew generally fabulous as is the Viking standard.
Very convenient to front desk and restaurant, but still quiet. The port side on Basel to Amsterdam faces the dock or riverbank a lot when docked. I'd go for a starboard cabin so you can see the river and the other bank.