I have been to Longyearbyen twice on award tickets. Both occassions was back in the days when SK and BU competed on the route. Never managed to book an award stay at the Polar Radisson. But there are plenty of nice ways to spend the night apart from the Radisson. I would say Radisson Polar is really a booring hotel (rooms looks like a hospital from the seventies). Find one of those authentic places run by locals instead. And maybe go for dinner at the Radisson.

BTW I think Radisson always count sunday night as weekend pointwise??? Last summer I stayed three nights at the Radisson SAS Airth Castle outside of Edinburgh, totaled 30000 EB points (Fri-Mon).