I fly Delta, but don't know what Delta One is.
I do know that upgrading from coach to "preferred" seating just to go from Atlanta To LA is $80 and it seems the only difference is that you are closer to the front of the plane - in my case, based on the available preferred seats, it can be as little as 2 rows closer! And the Comfort+ seats for that leg are $125. That's just too much money. Especially since to really do me much good I'd need it from LA to Honolulu as well and, of course, the non-stop from Honolulu to Atlanta. Those last two are already filled, but I would guess if they were available and you added them all up, you'd be paying about $500 more which is over half of my total cost.
I'd love to fly first class. In fact, some years ago I was set up to do that because my frequent flyer brother gave me enough of his miles to do so. And then Delta totally screwed up. Told me on the phone it was all set (And I made sure they said it was first class) and I just needed to enter my confirmation number on my computer to finish. When I did, it came back saying I needed almost double the miles it was supposed to be! When I called back (different person, unfortunately), they said it was wrong and gave me another number - which was also far more than I had. Referred to a person higher up and they gave me another number of miles, but still too much. While I was waiting for them to check, I checked my account online and they had scheduled me for 3 trips at various times instead of the one round trip. Couldn't get satisfaction from them, so I sent an email to customer service. They thanked me for my report and said it would help them make improve their service - but they didn't actually do anything. Then I mailed a letter to them. Same formal response. Finally I found out they had a new president so I sent him a letter and in it specified that I didn't want it just forwarded to customer service because I had already wasted my time with them. So, of course, I end up with another form letter from customer service!
I'm not happy with the airlines at all and haven't been for years. Ever higher baggage fees, added cost for meals, etc. So, I only do these trips back home once a year.