My son, 9 year old, wants to go to the beach next weekend and see/catch crabs. I want to do a little surf fishing and the wife just wants to hang out. We will most likely be staying with family in La Porte. Where should we head to for the best chance for the kid to have a good time?

Bay side would be easier. You'll have to check what is legal now since I haven't done that in many years. Sometimes we could just throw out a chicken part on a rope and ease them back in. I assume you can still use traps. I'd look for a place that you can wade into maybe knee deep or deeper water and lower a trap. Come back and check it after a couple or several hours.

Crab & Ghost Shrimp regulations from TPWD:

Crab & Ghost Shrimp Regulations

We've had good luck with chicken parts off jetties using traps. Wife tried to get some with a trap and a "wafer" (buy them at bait shops) in a canal last year and it didn't work so well.

ETA: As for a "spot", a jetty with an adjacent beach, like the end of Mustang Island State Park between Port Aransas and Corpus, would probably satisfy all. You can fish off the jetty, kid can catch crabs off jetty, wife can hang out on the beach near the jetty. But it can get crowded in places like that.

Mustang Island State Park

Get to the North side using Access Road 2

Edited again: Sorry, just saw you mentioned La Porte. But there are places like this along the beach in Galveston.

Holiday Inn

Get a sand pump and let your son catch ghost shrimp in the edge of the surf. They have fun and you get bait.