I see that no one has responded yet, so I thought I'd pass along that my husband and I used the rental car companies that book through the cruise line's shore excursion department. You might save $5 a day or so in each port, but is that really worth your time? I think not. In each port where we rented through the cruise line, the paperwork was done ahead of time, and we simply left the ship, the shuttle was waiting right there, we got our keys in the shuttle, and we were off to explore the wonders of Hawaii. That's worth $5 any day in my book. Check out the Wal-Marts while you are there because they have the same souvenirs as the gift shops for about 1/3 of the price, especially on the coffee.