Rent a golf cart for $80.00 for 3 hours and drive Catalina island...it's gorgeous!! You get a Map and it's very easy to get around..
No cruises added
I suggest taking the $2.00 shuttle downtown and just sight see on your own, the flee Market is annoying, they harrass you to buy stuff and the blow hole is just OK...
Don't purchase the on board excursions, you can purchase tours and golf carts, etc... On shore for very very cheap on your own.. Much less expensive!