Highland Village - Kids Kastle (Unity Park) has bathrooms, 2 play areas, and a pavilion.
Lewisville's Central Park has 2 play structures (one for bigger kids and one for little ones, along with bathrooms, a pavilion and a gazebo that little one's like crawling around.
Flower Mound's Rheudasil Park has a pavillion, and a nice playground, but no bathrooms and although we love the pond, it can become a bit of and issue with the little ones - it would depend on how many helpers you had for the kids.
I don't know of any parks in the area that have rubber mulch and a pavillion (or picnic area).
By the way, Family eGuide did a special on some of our local parks in their November 14th issue. Go to www.familyeguide.com and click on archives to view. There are even pictures of some of the parks I mentioned.