Chase Visa Signature Mileage Plus

A fairly new card for United airlines. Gives 40,000 miles on sign-up, single miles on most purchases, double miles on others (groceries, etc.) Annual fee is ~$50-100 (waived first year) Not too many perks on the airline itself; there are occasional random offers, like a $75 off United Flight coupon. Having a Visa Signature is nice, too.

Delta SkyMiles Gold American Express

A great card if you're flying Delta a lot. Signing bonus of 40,000 miles, then one mile per dollar, double on Delta purchases. Lots of perks on Delta flights: priority boarding, free bags, and 20% off airline food/entertainment. Annual fee is in the $50-100 range, but waived your first year. American Express has amazing customer service (replaced my card within 24 hours after I registered it stolen), and some general perks (concert presales, etc.) Unfortunately, lots of places in the Bay Area do not accept AmEx…

Capital One Venture card

The Capital One Venture card is one of the best cards out there if you want to earn airline miles. You get two points per dollar, and can then redeem them for flights (as well as other things) at the rate of 1 cent/point. I.e. a $500.00 plane ticket costs you 50,000 points. This is different from most other airline credit cards, whose award-miles-per-flight rates vary wildly depending on demand. For example, even though the jetBlue credit card gives you 1 point/dollar, it turns out that when you redeem points for some flights, each point can be worth as little as 0.75 cents/point.

According to NerdWallet, the Southwest Airlines card is really good: 25000 miles on signup, 1 mile per dollar, double that on Southwest expenditures, and 3000 mile annual bonus. There is a $69 dollar annual fee, and Southwest tends to be relatively light on the perks that you get for flying with them a lot.