you should definitely go to the parks with extra magic hours. as you mentioned your hitting it in (semi)off season so the crowds shouldn't be terrible and you get an extra hour in the parks over it. regarding fastpass+ i don't recommend it. as you said your already going during off season, you should still be able to easily get plenty of fast passes at the park for any ride you want. on top of that, having to plan every aspect of your vacation before you even get there takes away from the fact your on vacation lol. throw in some spontaneity and choose your rides when you get there.