Great little nature museum for the kids and lovely trails for all abilities. They also have a zipline and ropes course for adults and older children.
Fabulous botanical garden! Make sure to check out the Christmas Village and see Santa if you have little ones. The STEAM centered children's garden is also so fun for kids and adults alike. The 12 Days of Christmas gazebos displayed around the arboretum are super cool too. You can also bring in your own picnic and beverages (including alcohol).
For all of your shopping needs make sure to check out the Allen outlets not far from Mckinney.