My family and I always fly out of Orlando to NYC in the evening so that we can squeeze in as much Disney as we can. On our last day, and since we too have a rental, we get FP's at a park in the morning before resort checkout. We then head back to the resort, wash up, and get everything in the car. From there, we'll either hit a resort or Disney Springs for lunch. After that, we usually have a few hours to spare. This year we went to MK for FP's in the morning, We went back to the resort to wash up and pack the car. From there, we went to Disney Springs for lunch at Wolfgang Puck Express and then headed to EPCOT for snacks that we had left over from our dining plan. All the while, keeping a close eye on the time of course. But since our flight wasn't until 6pm, I thought that heading to the airport at 2:45/3:00ish would be OK.
After EPCOT, we drove around Celebration for a bit and then headed back to Disney Springs. We walked around for a while, went into the shops, and took a nice long leisurely stroll through the entire area. Then the doom and gloom of leaving set in and we had to go. Only to get to the airport and find out that our flight was delayed 2 hours!!!!!!!!!
Just plan something and enjoy the day before going to the airport. There is plenty that you can do. Next year on our last day we're getting on the balloon at Disney Springs...it used to be called Characters in Flight. Have fun!