Jeff, it really depends on when and how much time you have. For Athens, don't miss the Parthenon, the Archeological Museum and Plaka. Don't spend more than 3-4 days in Athens as it gets tiring with all the traffic. For Crete you really need to travel from one side to the other since it's a very beautiful and diverse destination, Hania is my favorite but for really amazing beaches you need to get to both Kissamos (west side) and Elounda (east side). You may want to avoid Chersonisos (Towards the east), it is known for the drunk tourists and its spring-break-style parties. In any case, people are very friendly and english language is quite popular as well.