Be sure to read the fine print on these. THey have some very strange restrictions on them. For instance, on our trip (5 more days!) we're taking a cruise afterwards and the fine print on these specifically states that you can't use them on a cruise. What's up with that? That's just one example.
Here's their list of limitations:
Usage Limitations
TravelFunds Cards are prepaid cards. They are not intended for use in certain industries. You are NOT permitted to use the TravelFunds Cards:
To reserve a rental car, or when picking up a rental car. However, at the end of a car rental, you can use your Card to pay for the rental.
To reserve a hotel/motel room, or when checking into a hotel/motel or other lodging establishment. However, at the end of your stay, you can use your Card to pay for your stay.
To pay for gasoline/petrol at the pump through automated terminals. However, you can use your Card to pay for gasoline by presenting the card in the station or to a service station attendant.
To pay for person-to-person internet payment products such as Paypal, YahooDirect and C2it.
To pay for telecom charges (including cellular, airplane telephones, payphones, home phone service, etc.).
To pay for recurring charges, such as health club memberships or subscriptions.
To make installment payments in the future for goods/services received in the present.
To pay for bail bondsmen.
To pay for detective agencies.
To pay for home repair services such as plumber, electrician, painter/decorator, etc.
To pay for internet electronic services including electronic mail, internet service provider, internet telecom, etc.
To pay for personal services such as escort agencies, introduction services, massage parlors.
To pay for wholesale goods.
To pay for on-board cruise charges.
To pay for gambling.
We reserve the right to add additional merchant or purchase categories to this list at any time in the future.
More info here:
http://www10.americanexpress.com/sif/cda/page/0,1641,18622,00.asp