What activities would you recommend for a "break" day between park days?

My family is planning to travel to Disneyland in early November. Our son will be about 4.5 years old. Last time we went we did 3 park days in a row and it was pretty tiring, so this time we would like to have a break day between park days 2 and 3.

Since it will be November it seems like it will likely be too cold to swim, and we did a character meal last time and don't think we want to do one again. While we will try to do some relaxing, I don't think I can convince our preschooler to actually just relax *all* day.

Does anyone have any recommendations?