4 week road trip in USA which card(s)?

zaffi

hi all, getting married in las vegas next year and will be in states for about 4 weeks. Will have a fair amount of cash saved by then and we're looking to part with as little of it to charges/load as we can.

have a flex account - but not after november so that's out

looking at dedicated dollar bank accounts - citibank has one with no fees or load but the exchange rate isn't as good as visa (today visa 1.581 v 1.564 for citibank)

assuming a ball park of £6K (each) that's a difference of ~$100

also looking at the clarity cc seems not too bad - i assume the mastercard rate is similar to visa? but unsure how much interest we'd generate on £6K worth of withdrawals?

as for pre-paid never used them seems on here as if fairFX is the pick but from travelmoneymax it's rate today is 1.553. which is $165 and $65 worse than other two rates respective - plus withdrawl charges.

can anyone help find us a card that's not going to stiff us!!