No, you can't directly redeem AAdvantage miles for cash back. However, you can use your miles to make a donation to several nonprofit organizations through the American Airlines portal. Can you pay for a hotel with AA miles? Yes, you can use AAdvantage miles to book hotels through the American Airlines portal.
100,000 Delta miles are worth an average of $1,120, according to WalletHub data. You will get the best value for your Delta miles if you use them for flights booked through Delta, though there are a few other redemption options to choose from.