Flew SEA to HNL on 10/31. Was monitoring seat assignments in F for a week before and consistently saw 8 seats open on a 737-900 so was really hoping chances for an upgrade were good. When gold eligibility opened I moved myself and companion to premium seats no problem. (I partly did this because I didn't trust them to keep me on the upgrade list from the exit row). Was showing as 1 and 2 on the upgrade list. Got an "You've been upgraded" email about 2 hours before the flight while in the lounge. Picked two seats in first but could not get an updated boarding pass which concerned me because of all the experiences listed above. Asked lounge attendant to print up new boarding passes but they showed no seats assigned. She said the computer showed us assigned to the seats we had picked. At this time I saw our names on the "Awaiting Seats" list and not on the upgrade list which I thought was strange. Went to the gate and asked for new passes. First set printed showed no seat assignments. After some further work by the supervisor we finally got boarding passes with our seats showing. I think the lesson is check your boarding pass and be persistent.