It depends on your own preferences. Fot the US, we take about $500 cash and credit and debit cards. NO Traveller's Cheques, which we find pointless in the US and bit of a pain. Cards are widely accepted in the US and ATMs are everywhere. Just remeber to tell your card companies that you are going abroad so that they don't put a precautionary stop on them.

But we do take TCs to Europe where Cards are not as widely accepted as in the US or UK.