I saved a lot on our APs last month. I think it ended up around 25% savings overall, but that included a couple hundred in rewards I had from our Disney Visas.
I got the Amex Blue Cash Preferred with the $150 bonus after spending 1k. It pays 6% at grocery stores up to 6k per year, so it's perfect if you're getting fuel perks as well for buying gcs. (It does have a fee; different people decide different ways on how they count the fee against the cashback/bonuses so that's up to you.)
It is best to buy Target cards at the grocery store, then buy Disney gcs on Target.com, but you will need a Red card to get the 5% off online (you don't pay with it if you're using the Target gift cards, you just have to have it as your default method of payment and you will get 5% off.) You will also need some time because with 4x fuel points you may get more points than you could use before they expire buying so many, and you can only buy $150 in Disney gcs at a time on target.com (though you can do several transactions back to back) and it takes about a week to get the Disney cards in the mail.
You will also end up with tons of $50 Disney gcs instead of fewer larger denomination (my Kroger sells the ones that go up to $500). That annoys some people, but I have paid for APs several times with $25 and $50 gcs with no problem.
I also counted my fuel points savings as cash back for my APs - If I saved $25, I put that $25 into my
Disneyland fund, i.e., I did not count the discount twice by buying gcs and counting the fuel perks as part of my discount, then also thinking I got cheap gas.

$2076 4x Deluxe APs
-$150 Amex bonus
$1926
Buy $1926 in Target gcs with 2x points =3852 - bumped to 4000 with milk and whatnot for 4 fillups at $1 off/gallon = $25 savings per fill up [that's filling 2 cars at once for us] for $100 total fuel perks savings
-$100 fuel perks savings
$1826
-$115 6% grocery cashback Amex on $1926 Note: don't buy them all at once or they may not count it as a grocery purchase. Spread it out!
$1711
-$95 Target 5% savings on $1900 in gcs (they only sell $50 denomination)
$1616 out of pocket for $2076 value = save 22%.
You can do better than this with the 4x fuel points, and you will probably want to buy more gcs to fund food, merchandise, etc.