My perfect day would be as follows:
Pick up a coffee and breakfast sandwich at Choco late and drive Rt 3 to Thuya Gardens. You can drive up the Thuya road or travel a little further and park int he lots across from the hiking trail to the Gardens. With the short hike which has stairs you will see the beautiful Northeast Harbor views. Spend a few hours enjoying the beautiful perennials and trees along all the garden paths. Be sure to include the tour of the home of Joseph Henry Curtis.
A great time to have lunch on the terrace of the beautiful Historic Astico Inn just down the road a mile.
Traveling toward Northeast Harbor pier to have a wonderful, narrated tour on the Sea Princess.
Upon returning enjoy the small village for some shopping and on the way back if you have time stop at the Astico Gardens for some quiet water garden spots.
Returning to the Hotel relax some and then enjoy a walk downtown to Mt Desert Ice Cream for a special treat. It is on FireFly Lane but you will know it when you see the line down the sidewalk. After getting your treat sit in the park and listen to the concerts or just people watch and meet some new friends.