Be careful as to where you exchange US$ travelers checks to HK$. Two years ago, a HK friend wanted to exchange his AMEX US$ travelers checks at a Hang Seng Bank (huge bank with numerous branches). They told him the service fee was something like HK$100 per check! Not per transaction, but per check! So if you exchange small denominations such as US$20s, you lose over half of the value to service fees. What a rip-off! And he was a regular customer of that bank too! Ended up exchanging the AMEX checks at one of the local AMEX offices where the exchange rate was close to HK$7.70 per US$.