I've got a few...
1 - Spend more time in each country in Epcot. Our trip last year was the first for my DW. So we spent a ton of time at MK, and a day each at Epcot, Disney/MGM Studios, and Down Town Disney (which will lead me to #2 in a minute). It was drizzling and sorta miserable during our day at Epcot, so we just breezed through the countries. "Hey, there's Japan. Oh cool, Norway. Look, England. Ok, what do you want to do now?" Our trip in 379 days will be two days longer, so I am hoping to be able to spend almost an entire day just exploring each country's pavilion. I want to ride the rides, see the shows, eat the food. I really feel like I missed out last year.
2 - Go to Animal Kingdom. As I explained in #1, we spent the majority of our time in MK. We also spent a day just relaxing at our resort. So we never even got to Animal Kingdom. That's going to be our first stop next year.
3 - See more of the parades and evening shows. We only saw the parade and fireworks at MK. I really want to stick around Epcot to see the fireworks and laser show. I remember when I was a kid how cool it was to see Spaceship Earth turned into a giant globe. I really want to experience that again.