I can't say for Svalbard, but for OSL-TOS I'd sit on the right hand side, i,e. an F seat as the flights usually follow the coastline and weather permitting you have some nice views of the mountains and fjords. For TOS landings on runway 01 the right hand side is great (just did one yesterday), but if the wind is from the south and runway 19 is in use then an A seat is more recommendable because in that case coming from south the approach basically takes you around the main island where the central city is located and then a 180 degree turn to the left to line up for landing. From the left hand side you have great views of the city proper.