I'd do my second day at either the MK or Epcot depending of which sounds better to you. If I were traveling with my son who is 25 it would be two days the the MK for sure. He is in love with that park. There is a lot to do their and repeats are fun. I am traveling with my 84 year old dad in May and with him, I'm doing two days at Epcot for flower and garden. This will be nice for us as he uses a scooter at the parks - the slow park rental one -- so with two days we can take our time, hit all highlights and garden displays leisurely. We will also with this plan be able to do leisurely dining at the park. With one and only one day at a park, we just to table service to minimize time spent dining.