If it makes you feel any better, I can't book a USA internal flight from Hong Kong - they want a USA address and credit card.

Cebu is quite good, but remember they are a budget operator - flights are very cheap. Very new fleet. They are using the new Terminal 3 in Manila for domestic flights, which is a massive change from the old domestic terminal.

A word of warning, the flights can be delayed. So if you are travelling from one part of the Philippines, into Manila to get a connecting international flight, you might want to leave yourself at least 3 hours connecting time. You will have to change terminals also.