Ashbridges bay is pretty small compared to J.C Saddinton. If you ride Ashbridges a few times you wear it out pretty fast. I ride J.C Saddington park 3-4 times a week, and I am always finding new lines.
JC Saddington is more technical, and the terrain is more varied. You have the big moves up rocks, and you have the long tricky comp-style lines. There is a small river rock section for those brave enough to go near the water. There are also some nice man-made sections within the park, including a spot where you can go up the side of a house, and a nice spot to practice sidehops/taps.
There is also lots of urban right near JC Saddington park, and spots where you can break for food/drinks. A church right near the park has a sidehop wall that steps up from 32', to 54" pretty much in two inch increments. There is a concrete spot that has some nice taps. More sections than you could realistically spend a day exploring. It's definitely worth saving some energy and staying to ride Sunday.