If you are putting it into a USD account here ask about any charges they may have, specifically about transfer charges. You might find that there are charges of 1-2.5% of the transaction amount to transfer to an overseas account, particuarly if you are transferring large sums, i.e. over $25,000.
Also ask exactly what the process is for trasferring your USD elsewhere. You might find that there is some daft rule that during the exchange, the USD in your account is transferred to GBP and then transferred back into USD at the other end. (I wouldn't put it past Barclays).
Avoid putting all that cash into someone else's business account. It might sound easy, but if that business goes bankrupt you would have lost the lot - the minimal gain is not worth the risk IMHO. (I'm not suggesting that Capt. Gentil is about to go bankrupt, but there is a standing warning here on PPRUNE never to pay upfront, and as far as I am concerned, a transfer of savings amounts to the same thing).