This is what I use when I travel, and I couldn't be happier. I bought mine at Costco, but they can also be found at places like this:
http://www.pcconnectionexpress.com/...61-_-New-_-GY16&ci_src=5784816&ci_sku=8459561
It's a 3 outlet surge protector with two usb charging sockets. In addition, the plug head rotates so that you can position it vertically or horizontally. I used it on my last
Disney cruise and it worked out great, plus you have the safety of it being surge protector.