To be 100% sure you get it you have to buy the FC seats

As for Upgrading every fare except a Y which isnt cheap you need to pay a co-pay and miles along with that (except maybe an H, H Intl usually has no co-pay but does to HNL, $200 each way).

Now the chance of getting an upgrade even with a Co-pay and miles isnt easy, especially if CO knows it will have no problem selling the seats as revenue setas. So usually its not till the last min that CO releases seats into the Upgrade pool.

Thats why I do not buy anything but the cheapest Coach that I can, the last thing I want is to be paying alot more $$$ and still end sitting in the same coach seat I could have for 1/3 the price. Unless CO tells me at the time I purchase the tkts that they have Confirmed Upgrade space available, then Ill figure out which fare basis will get me into the FC cabin for the least amount of $$ outlay.

Also when you call CO you better be flexible, so if you can go on 5/10 and 5/10 only your chances will be slim to none with none winning out. If however you tell CO Im looking to fly EWR-HNL and want to upgrade using miles and Im FLEX and looking to fly out around 5/10 but can go before or after and want to stay for a week or so . They will then tell you what if anything is available

Good Luck you will need it