There are several dog parks or dog friendly parks in The Woodlands, also one of the pet spa's (Pink Poodle) in Old Town Spring has an indoor area available for meet-ups. The same is true of Kingwood, Jaime at Pampered Paws has let us have meetups at her store too. Good luck, with a little planning it's a blast!
Heres a link that might help:
The Woodlands Dog Park Club