Other things I've remembered are, if you are there in high season, take mosquito repellant (we were there in September and it was OK). Hersonissis is (apparently, I have no evidence but heresay for this) the male date rape capital of Europe, DYOR.
We visited:
Knossos
Malia (the palace there, less developed than Knossos)
Rethymnon (Interesting town, you can take the regular bus service from the road through Gouves)
Iraklion (V good museum, and very interesting city. Continuously inhabited for something like 6000 years)
Samaria gorge (never visited it, but it's supposed to be good)
The mountains are spectacular, and there are caves everywhere, we hired a scooter for about a week, but I can't remember now where exactly we went. There is a plateau up in the mountains that was spectacular, Lasithi Plateau
Spinalonga leper colony, lovely island.
Things to watch out for:
Truely dreadful driving (but the roads were fairly quiet)