Right now, using just one card will get you 60,000 Chase Ultimate Rewards points – enough to go on a free trip to Europe.  Annual fee waived for the first year if you apply at a Chase bank.  This is definitely enough to get you somewhere on United, you can even pull 1.5 trips out of the redemption instead of 1.  Here’s a quick lazy itinerary – 60,000 points Chicago to Paris; the card plus $129.