V.P.
Wow! Lots of great places to go on Halloween..
We primarily feature activities in Lewisville, Flower Mound, Highland Village, Coppell, Grapevine, etc., but be sure to check out our calendar. Here's the link for Halloween Day: http://familyeguide.com/user_vcalendar/day.php?day=2009-1...
If you don't want to drive to this event from Irving, I would use the list as inspiration... If our Michaels is having a Halloween event, maybe your Michael's is as well. I would definitely check Irving's rec center, the library (one of the Carrollton locations is giving free books as "treats" to kids who come in costume).
Dallas Arboretum is having a Family Fun Weekend as part of their Great Pumpkin Festival that weekend.
WinKids in Highland Village is having a huge event that day as well - FREE.
And don't forget the pumpkin patches! Your son is the perfect age to enjoy this fun activity all month long: http://familyeguide.com/Flower-Mound-Pumpkin-Patches-DFW....
Good Luck! What a perfect age for Halloween fun!