Upgrading--or even trying to upgrade--is a mistake as the previous reply posts very politely note.

I just want to be more emphatic. DO NOT UPGRADE!

Even if possible it will not get you a bonus and thus there is no good reason to do it.

Apply for a Citi AA card with a 50K or so bonus, and do the same for the Chase Sapphire Preferred (40K bonus of valuable ultimate rewards points which convert to UAL miles) and a Chase UAL Explorer card (50K UAL miles). Just be sure you can meet the needed spend on each card for the bonus. To do this you may need to spread out your apps as you usually have only three months to meet spend.

Good luck in our fascinating hobby!