We had this dilemma on our trip... nearly the same times you mention, too!
What we ended up doing was, First Night was a "relax-in-your-resort" day because we weren't in the WDW area until 4:30-5pm. We had a small gathering in our hotel that night, but if we'd had tickets to MMNSSHP, we would have headed out to the park.
Last Day, we had to be at the
MDE bus stop by 1pm with hardly any park time, so it was a quick hop over to the Contemporary to eat at Chef Mickey's and then visit Disney Springs, then we caught the bus back to the hotel, finished packing everything, and lounged around the resort until the MDE arrived.
TL/DR; Enjoy your amenities, you are paying for them and they are there to be appreciated! Yes, it's all about Mickey but it's
really all about having a great time! Who says, "Wish I hadn't lounged by the pool for 30 minutes"????