Re-think the debit card idea, especaiily if you are not required to put your PIn into the little black box. Most cards today do not require that, unless the merchant exreslly identifies the card, and enters the data, as a sdebit, rather than a credit.
Unless yours is one which limits your liability in case of loss or theft, you could be in for a very unpleasant surprise should you lose it or even worse, the number falls into the hands of someone less than honorable. Instant wipeout.
Take the credit card and pay if off with the debit card when you get home. :p