Last I heard Hawaiian has the only mileage mall that supports Amazon.

Some cards with rotating categories give 5x on Amazon periodically. For example, the Chase Freedom card has announced that Amazon will be one of its 5x participants in the last quarter (Oct-Dec) of this year. Chase Freedom earns Ultimate Rewards points, which cannot be redeemed for airlines/hotels if you only have that card, but there are certain other (annual fee) Chase cards that you can add which will let you transfer any points you earned with Freedom to airlines/hotels (that Ultimate Rewards supports). However, you can't apply for generic (non-partner) personal Chase cards if you applied for (more than) about 5 cards (from any banks) in the past 24 months.