Citi's AAdvantage Platinum Select card is back with a boosted sign-up bonus, and this is one you might not want to miss if you're looking to boost your American Airlines mileage balance! Right now, you can snag 80,000 AAdvantage miles after spending $3,500 in the first four months. That's a pretty sweet deal, especially since it's 5,000 miles more than the usual elevated offer. Why should you care? Well, 80,000 miles can get you a long way – think a round-trip ticket to Europe or several domestic flights. Plus, the card has some nice perks like a free checked bag on American Airlines flights. There's a $99 annual fee, but it's waived for the first year, giving you a chance to see if the card's benefits outweigh the cost. Note that if you've earned a bonus on this specific Citi AAdvantage card in the past 48 months, you won't be eligible for this offer. There's also an interesting perk that may be useful to some. If you spend $20,000 or more in purchases during your cardmembership year and renew your card, you'll earn a $125 American Airlines Flight Discount.