I'm always trying to work the travel rewards! We travel a lot for work, so I really try not to spend anything on vacation air fair.
If Southwest is offering 50,000 points again, that is a great offer. Depending on the redemption points for flights, you can take 3 or 4 round trip flights on 50,000 points.
I also like the Barclay Arrival card. I opened mine in August or September and they offered 40,000 bonus points or so. You can redeem those points for a $440 statement credit. You earn 2 points per dollar spent and no foreign transaction fees. Whereas the Disney card, Southwest, and Delta Amex typically only award 1 point on most purchases.
Delta AmEx Platinum card offers one free companion flight per year. The fee is $150/per year, no foreign transaction fees.
There are a few websites that compare travel reward cards and programs. Take a look and see what the current promotions are.
I have the Disney card without the annual fee just to get discounts on tours. *ETA* Otherwise I don't think the reward program is good.
Good luck!