I am going to Alaska in June 06 and using my debit card since i have no credit card. I have done my research on the subject:
Know your daily limit, and if you dont think it is high enough for your trip - call your bank and ask for a higher limit. My daily limit on my debit card is $1,400.00 in any 24 hour limit and the bank says the clock rolls over at midnight.
Inform your bank where you are going and alert them there may be purchases outside your normal travel area. I called my bank yesturday and spoke with them...they told me they were more suspicious about large purchases out of the country.
Just a good thing to do is call your bank and tell them your plans and they can tell you their policies, etc.