Not sure if you're doing Crete in general, or just Chania. Was on Crete for 10 days on my honeymoon five years ago.
Chania is great. Very cool old town to explore with lots of restaurants. Nice little museum that includes some WWII stuff, if you're into that (there's a small town on the island that has the most ridiculous private collection of WWII artifacts imaginable). If you're staying in the old town and have rented a car, be prepared to have to park it outside of the old town and pull your luggage.
Crete in general is fantastic. Very diverse geography, so much history, lots of cool little towns, restaurants, beaches . . . Hell, even the little roadside stands that sell their own plastic jugs of homemade olive oil are fun - they'll give you a shot of raki just for stopping by.
Give me some details or shoot me a PM and I'd be happy to make any suggestions. Someone on this forum, before I went, suggested I follow the Germans. Very glad I did - found the coolest little town on the South side of the island, very romantic and had one of the best meals of my life there.
