Opening an account should be no problem - I had one up until last month and it was VERY useful when in the US. It came in handy at the supermarket and avoided me paying credit card charges. He'll probably need loads of ID though.
He might want to try someone like Citibank. They do a US Dolar current account that he can have based in the UK. Then it may be possible to withdraw cash in the US without charges. He should also be able to transfer money from a Sterling account into it to avoid expensive international transfer fees. Never had one myself but you should check with them.
www.citibank.co.uk
A lot of banks in the US are regional, so if he had an account at a bank in FL, if he takes you up to NY for the weekend (!) there might not be any of that bank's ATMs he can use - he'll end up paying a fee anyway to withdraw money. My bank was in CA and I had to pay $2.50 each time I withdrew cash in FL.
They do tend to charge for everything though (for new cheque books, if the a/c falls below $1000 etc.) do read the small print before opening one!
This actually might be better in the North America forum...
All the best.