Another +1 for blockchain.info
I know we shouldn't trust anyone, but as far as usability goes I think blockchain.info is the best out of any I've tried so far, nice features.
Just keep an offline wallet for the majority of your coin and you'll be good.
I like how the custom send menu has an option to send the return change to the same address you sent from. This lets me activate a paper wallet and still have it remain a valid backup of my key.