Saw the Nuggets vs. the LA Clippers and there were lots of empty seats, we got two tickets for $20 in 304, row 8, seats 19 & 20. Would have been nice if we could get down on the lower level during the 3rd period but they have ushers that watch the entrance to every single section.
I talked with an usher there and he said they sometimes go around the Pepsi Center before the game when they have tickets leftover and offer fans free upgrades. I'm going to have to do some more research on this.

While section 304 was way up there you still get a good view of the ice. I've sat in quite a few places at the Pepsi Center and haven't found a seat with a bad view. The neatest thing of the arena is the statue that has both hockey and basketball players compiled into it. Bring your camera!