One good thing about multi-day passes is that additional days are much cheaper than the first days. It won't cost you that much extra to go 5 days vs. 4, at least as far as park admission is concerned. I would also recommend getting to the park 30 minutes before it opens. They usually open Main Street at the Magic Kingdom 30 minutes before the rest of the park. Just being on Main Street is fun, even if you're not riding. Then I'd stay in the park until a cast member asks you to leave! That happened to me about 10 days ago on my last day at MK! That way, you'll get the most of your park admissions!