Amex HHonors Hilton card (free) gives 5 points for $1 in any restaurant.
People here value HHonors points at .6 - .8 cents, so cashback is 3% to 4%
What's nice it can be registered for Rewards Network (frm. Idine), so HHonors points will be on top of miles or cashback.

Finally, Amex give a different account# for every cardholder, so the same Amex account can be registered with different airlines.