We just got off the GC last Sunday with a rented boat package from Moenkopi, which included a 200 qt Galaxy (now Canyon) filled with 10 days worth of frozen meals. It performed superbly---I threw away big chunks of ice at Diamond on day 16.
Because I had the room, I took my Yeti 120 filled with block ice (the good ice), kept it frozen with dry ice for cocktails, drained it daily and only opened it once or twice in the evenings. I was out of ice on day 10. I couldn't believe the difference in ice retention between these two coolers. What's interesting to me is that I had the lid opened far longer daily trying to ice pick and rubber mallet the layers of meals out of the Galaxy. The last 4 days I added a case of warm beer and passed them out to the group, still had plenty of ice.