Add the holiday levels to play all year.
Only add the gifts, extra parts etc during the holiday.
The winter level was a blast trying to get through all of the different directions to go.
I didn't see the other holiday levels so I don't know if they are the same as the winter one just decorated differently.
If they are the same with decorations, then make it Earth 2.0 and leave it grass until the next holiday decor.
If they are different then it would be cool to try them all out even without prizes.