I recommend to use Blockchain.info or BitGo or GreenAddress over Coinbase if you already have Bitcoin.
With those services you hold the keys to your Bitcoin, not Coinbase. With Coinbase they are in control over your Bitcoin, not you.
GreenAddress is the only wallet for Bitcoin with a 2-2 model Multisig offering a Bip0032 wallet with nLocktime on the Bitcoin blockchain.