I'm not a first class flyer person, so I can't address that--I don't fly enough to get first class upgrades and the flight experience for me, for a less than 6-hour flight, is not that important to spend the money on upgrading. That said, I've flown ATA roundtrip three times between the west coast and Honolulu in "steerage." It's like flying in a big bus--but really, the service was not bad, at least when I flew. No amenities (although they did do the warm washcloth thing near the flight's end--maybe they've stopped?); flight staffing seemed variable, some really nice attendants and a few stinkers who didn't seem to care much about passengers other than doing the minimum of their job.

All six legs of the flights arrived and left on time. No baggage loss. Acceptable cleanliness. One time the plane was new and only on its second ATA flight--that was a nice one.

As far as how many folks will be flying from Ontario to Hawaii in August--in my experience with ATA and Southwest, they generally fly pretty full flights 'cause that's how they're known for making their money, but I'd check it and see ahead of time to determine your chances of upgrading for a price if that's important to you.