My personal decision point is, if <$800 then pay money, if >$800 then use miles (40k saver first). For $623 I would personally do it.
It would be better if you could route YUL-EWR-HNL, as the long segment would be lay-flat. But I doubt that's available for the same price. Still, 9h on B777 is better than flying the same distance on a B737.
Another factor for First vs Econ is the new 777 Domestic reconfig...if ORD-HNL becomes one of those (see
777-200 v5 seatmap), then Econ will be 10-across, 17" wide seats. And lay-flat in First.
Happy travels!