Not only for trips to the US but also at home and especially when buying off the internet.

many people now have upwards of £3000 (one of mine has £10,000) card limits

i suggest (if you havent already) you obtain a new credit card with a maximum £1000 limit (or less)

use this card solely for purchases abroad or over the internet and then re -imburse it immediately by telephone with a payment from one of your other high limit cards, that way if your card id is stolen the most the crooks will get off your card is £1000 (or whatever limit you set).