Barclaycard has probably the best 2% rewards for travel of any card. I got a big 40,000 mile bonus when I signed up last year, not sure if they still have it.
You also get 10% back when you redeem your miles. I.e. Redeem 20,000 get 2,000 rewards.
Also, they are the easiest rewards points I've ever seen. You use your card for any flight, gas, hotel from any site, and then redeem it from your card. No booking from certain sites, airlines, etc.