Can't really get into the play date thing because things are just too hectic. And my children are in Houston or with other family just had my gallbadder out so trying to rest you can see I'm bored...
Just a few things I have found over my life-time as a mommy here in SA:
My advice to you is to get a Zoo family pass as low as 50 or 60 dollars. With all the kids is pays for itself the first time. We have had a membership for 4 years and it great. They have a little water hole where the kids can swimming.
The Witte (on Broadway) is free on tuesday after 3.
Kidstown on San Pedro has summer offers.
Maybe a VBS for the older kids.
The library and some restuarant have summer reading programs where they recieve free prizes/treats.
AMC theater last year had a free movie on Wednsday mornings at 9.
Hope this helps and check out the weekender and Kids Magazine @HEB or Walmart.
Have fun and be safe.
L.