I concur with eMailman and ILuvParis on the Rijksmuseum and the Ann Frank House, definitely recommended.
For airport transfers, trains are the fastest (10-15 minutes to Amsterdam Centraal) and most convenient, they leave from underneath the terminal building, cost $2.50 one way, and run every 10 minutes or so. Otherwise Amsterdam taxis are priced within the European average.
Also, the tramway passes are very good deals and convenient if you want to take advantage of Amsterdam's excellent public transportation network.
As for getting Dutch guilders, I recommend using ATM's. Most change shops have either very bad rates (e.g. Thomas Cook) or charge a fixed commission (e.g. ABN Amro at the airport - bad deal for small amounts). Don't forget to change all of your money back into dollars when you leave, guilders will only be accepted at banks after 2/28/02.

[This message has been edited by monahos (edited 09-10-2001).]