I find places that do cheque cashing, pawning etc give a better rate than the likes of the Post Office and most travel agents. Me and the bf got ours from 'The Money Shop' (I think they're a nationwide chain) He got 1.63, I got 1.62. We decided to bite the bullet a few weeks ago and just change the cash we wanted to take, I still plan to use my credit card in the US anyway.