Having just come back from Stalis - I would suggest - A trip on the happy train - gives you an idea of your bearings etc. Also a trip on Zorba's boat trips - booked from the Happy train station at the Malia side of Stalis.
Hire a car and then go to Knossos/Faistos/Lasithi Plateau/ Rethymnon and Agios Nikolias - boat trip to Spinalonga booked in Ag Nik ( its cheaper) - go on the Venus - English guide with an excellent knowledge of the island.
If you like wine, a trip into the mountains is called for - after you have been to Knossos ( its in the same area) - go to Archanes - wine producing village of Crete - bottles of excellent wine at 2 euros 50 that retail at 12 euros in the restaurants.
Water City/Aqua plus if you like water parks - hope this helps.

Thank you very much will look in to all u suggest, happy trains are so good one in portugal last year, will def have a look at the boat trip

cheers