Cash rebates are fine, but travel rewards can give you a good return per dollar spent if that is something you value.

I would highly recommend applying for the Chase Sapphire Preferred Card as it will give you 50,000 points for spending $3,000, and it gives double points on restaurants, travel, and transportation. These points can be transferred instantly to United/Continental, BA, Korean Airlines, Hyatt, Marriott, Priority Club, and Marriott. With the ability to fly out of ORD, you should be able to redeem miles on United easily, whether for upgrades or free first class international tickets. If you have the ability to get a business card, I would also recommend applying for the Chase Ink Bold Card, also part of the Chase Ultimate Rewards program with a 50,000 point sign up bonus, giving 5 points per dollar on the first $50,000 spent annually on office supply stores, cable, wireless, and landline services, 2 points per dollar on the first $50,000 spent annually on gas and hotels, and one point per dollar on everything else. If you just apply for those two cards, you will have 100,000 Ultimate Rewards points, enough for one business class ticket to Europe when transferred to Europe, and your annual spend would get you to a second free ticket soon (taxes on each ticket might cost you $100-$200). I'm not familiar with using points for upgrades, I just know it can be done if you book the right fare class.

Many people collect miles in one program in each of the three main alliances, for example United or US Airways in Star Alliance, American in OneWorld, and Delta in Skyteam. You can fly on different airlines within an alliance but still credit your miles flown to one airline frequent flyer program. Diversifying gives you more options for redemptions and allows you to collect more credit card bonuses.

I think your spend categories would be best served by the Chase Sapphire Preferred (a visa) and Ink Bold Card. Start there and then decide whether you want to earn in any other programs.