WE just got back. My 5 year old hasn't used a stroller for years, but on the advice of people here I purchased the Maclaren Volo.
The original plan was for us to use it just for evenings, when she would be most tired. Yeah, right!!! We used it every single day, every time we went to a park. We walked miles every day, and her legs are small so it was a LOT of steps.
Plus, in December, I'm guessing you'll have some sweatshirts and stuff, just in case. The stroller will be a HUGE help!!
Just a hint: bring an extra poncho to use for the stroller. I'm not sure how much it rains in December, but it was incredibly valuable in August, even before the tropical storm. We used an orange one, and could always spot our stroller