It is not easy for a non-citizen to open a bank account. At the very least you'd need a US address to start. A Social Security Number is also a requirement for any interest-bearing account (and in fact, banks will pressure you to provide one in all cases), and depending on how you would fund the account, you may need to be there in person. Partly this is because banking in the US is regulated by about sixty different government bodies, partly this is to combat fraud, partly this is because of various provisions of the Patriot Act regarding establishing identity, money laundering, etc.

Ask your bank in the UK if they have an affiliated bank in the US; if so, you may be able to open one through that partnership. Some banks, I've heard Citibank UK for one, offer dollar-denominated accounts. ING has a growing US presence, as does HSBC to a lesser extent.

Now, even with the massive consolidation that's occured in the last 20 years or so, the US banking system is still highly decentralized by world standards. As such, the part of country you're in will dictate which bank offers the most ATM options. Suntrust may have no rivals in Atlanta, but nobody in Los Angeles will have even heard of it; Wells Fargo may have an ATM every ten feet in San Francisco but not one within a hundred miles of Orlando.

Many Internet banks reimburse you ATM fees up to a certain amount per month. However, it may be hard to find a UK bank that has a partnership with someone like NetBank. The e-banks owned by brokerages (e.g. E*TRADE Bank, TD Waterhouse) offer similar schemes.