The Oklahoma Visitor's Center is just north of the TX/OK state line after you pass the gargantuan Casino. I've been stopping here for years after my long drive out of TX. It's well maintained and very clean - inside and out. Outside features include a scenic woodsy area, shaded picnic area, and several places to walk your dogs. There's also a separate area for big trucks, RVs, campers and trailers. Everyone inside is so enthusiastic and friendly.
Bathrooms are super clean with magical mirrors that make you look skinny. Maybe that's why I always stop here?!
If you're actually visiting the state and not just driving through, they have a wealth of free info for various attractions, and also lots of books for purchase. They also have a coffee station for the caffeine addicts. read more