Easiest way to buy Bitcoins with your credit cards in the US is Coinbase and Circle.  There are some verification hoops to jump through, but after that initial setup, it's all easy peezy.

Another alternative way to get Bitcoin using credit card is through https://brawker.com/.  It's a more roundabout way, using Brawker's online marketplace to fill an order to receive Bitcoins, but overall trusted by most accounts.