The extra cost is minimal. I highly recommend hoppers. We stayed on site last Xmas and we would go to one park in the am, go back to the room for lunch and rest, and then do the other park in the pm. It is nice to not be locked in to one park each day.
You could probably get by with the base tickets but you can upgrade to park to park once you arrive. See how the first day goes and take it from there. Just make sure you upgrade before leaving the park that first day.
You could probably get by with the base tickets but you can upgrade to park to park once you arrive. See how the first day goes and take it from there. Just make sure you upgrade before leaving the park that first day.