After our first cruise we went to MCO to catch our flight only to find out that it had been changed to 8:00 pm that night! So we rented a car and went over to MK for the day and had a great time (it was a Thursday in September, so the crowded were low).
So I would say yes, go and have fun! If you can stay an extra night, even better! This year we get off the ship on Saturday morning and we are spending that night at Pop Century and flying home the next evening.
DJ